I have not seen much mention of this except oblique mentions here.
It is called the failure cascade.
In robust systems, you can lose a lot of things before a failure happens. In your food system, if you do it wrong, and not even 'wrong' just not accounting for failure, your failure is a straight line.
That old chestnut saying for the want of a nail the war was lost.
This is because there was not a robust system in place to account for that.
Yes people say one is zero and 2 is one. But it fails to really clarify exactly the deeper meanings of the failure cascade.
As a recent personal example:
I had a typhoon hit my house. I have solar power as the backup and it can provide about 75% of my overall power needs if I manage it right. However on the day of the typhoon, I am home. Strike one.
I am using power as I am home. Using the PC, and cooking in the instapot. The shore power went out. So my system, went to battery. Cloudy weather, my system was only making a few watts of power. It was quite dark. But since I had no alarm that notified me of the shore power going out, I ran down the battery to a very low level, once I realized that the shore power was out. Now I was still with lights, because I have a separate backup battery system of lights using those outdoor solar flood lights. Except the panel is outside and the floodlight is indoors. So my failure cascade was stopped because I still had light, and gas stove.
But this was only because I had a robust system. I have since installed an alarm that sounds when the shore power is out. Even still I was one step away from being in the dark except for a cell phone light.
This is only a example. Bigger systems are more prone to failure because vertical integration is more efficient, yet less robust. Power, fuel, food, all these systems are being deliberately chipped away now. So while a few system failures does not a societal collapse make, a cascade of failures on the other hand brings it all down.
It is not the thing that you think will fail that brings everything down. It is the cascade of small things that brings it down.
this applies to personal finance, on the small scale to entire societies on the big scale.
It really depends on the personality of the person or people at the homestead though that dictates how robust the system should be. My personality is such that I just adapt and overcome. Sure, it is not what I want; when the power goes out, I just want to keep doing what I was doing, but the reality is, sometimes it is nice just to stop what I am doing, light a hurricane lamp and curl up with a good book. On most power outages I actually get a lot of sleep which is really nice.
But when I had four daughters and a wife here, electricity had a different importance. They were less willing to adapt, and so I had a means to provide for their way of life. I had a back-up generator, with a back-up to the back-up generator that can kick out 20 KW, which is plenty for my house.
As a person that is involved with grid-based renewable energy, I also know people have an expectation that when they flip a switch, power is there. For many in society, death can result if they do not have that. I get that, and I fully understand that for some people like the elderly or sickly, they cannot just adapt and overcome. For those people, I am glad there are low cost systems that can provide the electricity they need when the main grid goes down.
This is where people really must evaluate what their system needs are, and for the rest of us not to be judgmental. Without question I am in awe of people who coble microhydro systems together and have a stream make electricity for their homestead. But I fully understand if that same couple ends up taking in their elderly parent and need to install a 15 KW back up generator coupled to a 500 gallon propane tank because their father is on an assisted breathing machine.
What the original poster calls "robust", I simply call "insurance", and with insurance you always invest heavily in something you cannot live without. The challenge, however, is figuring out what exactly are "needs" and what are actually just lifestyle continuation wants. I propose, we can get by with far less than what we often think we need.
I tend to think ahead a lot.
When I design a system I think of all the problems it might have to deal with, and think what it would take to deal with them. How many things that will mitigate those problems can I either add now, or leave a way to make it easy to add later? And if I don't need to leave a way to add it, I at least leave myself a note to think more about it, and add it when I can.
Plumbing is my example. When I run water lines, I never use 90 degree corner pieces. I'll always make that junction a T and add a piece of capped pipe to the not in use side of the T. To me that's an easy way to make the system expandable when needed. I also add shut off points in multiple places. When I put in any kind of drain or sewer lines I put lots of clean outs.
Example of a failure cascade from lack of the plumbing stuff above: We owned a trailer park. I got called out one night for repairs. We had a massive flood going on. A sewer line got plugged, the clean out leaked, the resulting water flow broke the water input lines. There was only one heavily rusted water shut off that could stop the water flow. In the meantime, the flooding of water stopped up more of the sewer system for 6 or trailers, most of whom also had yards under water. I had to call for help, we had to make a stack of pallets (that still got wet) to put the sewer machine on to run the lines and get them moving. (We both got shocked multiple times by the wet sewer machine.) I had to dig up a water line uphill of it all, cut it, hammer a ball into it and cap it to stop the flooding, so we could cut out the bad shut off and replace it so we could fix that water pipe..... And I guarantee we repaired it all with proper clean outs and shut offs installed.
This was all very avoidable. That area had not been updated since we had bought the park, and the previous owners did the absolute minimum on plumbing. Updating it all in an emergency sucked. We had been going through and doing it all, but hadn't gotten that far. Knowing the system had problems is why I had figured out what size kid's ball fit tightly into those water pipes, so I could stop the water flow long enough to cap it and fix it right.
Think about how a system COULD possibly fail. What could possibly be done to mitigate that ahead of time? And if you can't do it now, what will you need to do it in a emergency? Have that stuff on hand, because stopping a problem early on in the cascade is a lot easier than stopping a whole cascade of failing systems.
Butte makes an excellent point. We need to aim to get our systems organised so that one thing going wrong doesn't make everything go wrong.
I think the "curl up with a book by hurricane lantern light and read" is also a good example of a "robust-enough" system.
That's a great way to spend a black-out evening. But if there's no fuel for the lantern and no back-up lighting, go to bed and sleep is the remaining available option. And if the person had an urgent piece of work that needed to be completed on computer and emailed off that night, they'd be screwed and seriously wish they had a battery back-up!
What we consider "robust-enough" depends on our needs and our life. I consider my needs are fairly simple, so my back-ups are on the small side and not super high tech. But I do make sure to have back-ups for my back-ups, as well!
Pearl, ugh! That sounds a total nightmare scenario.
I'm only 62! That's not to old to learn to be a permie, right?
Tangential but related, losing access to things will highlight what's important to you.
Example, one of my teenage kids "couldn't " go into the basement...until the internet went out.
I have an old gas stove, and I live in a place we're the gas lines are very dependable.
It once carried us through a stretch of winter when our furnace died.
I am nibbling away at a wood fired solution for home heating but I'm not there yet.
I hope to supplant propane with wood in our outdoor kitchen .
I'll keep the propane devices because of my partner (and because I love my Big Easy Infrared turkey fryer!)
Saving money/ the earth may not be enough of a motivation for me personally to chose wood over the conveniences of gas or electric, but flavor and biochar will be.
For that reason and because I have a short attention span, I'm looking towards tluds as well as rocket stoves.
I used to dream of using only rainwater in my household, but the amount of storage that would require made it impossible.
Instead I switched to a more efficient toilet and washing machine.
Now I'm hoping to store rainwater for thermal mass, irrigation and emergency supply.
Electrical resilience seems the hardest to me.
My house isn't well situated for solar, plus solar storage is expensive.
I'm hoping the used market will make a modest battery system doable
A generator that can burn propane is the most likely thing.
My father in-law lives next door and he has one.
I keep propane on hand for this reason in nothing else.
Family is my real redundancy plan.
I have a lot of tools and some knowledge, but mostly we live on goodwill and grace.
We try to earn that grace and pass it on.
This is probably a terrible plan, but it's the only one we consistently stick to...
I think having confidence in your lowest tech solutions leads to better resilience. The lowest tech doesn't have to be your primary backup, but it should be the first one you learn and implement before trying to get redundancies in place that are closer to your normal every day state of being. If you know you are perfectly capable of heating water outside on a fire, have the wood and pots to do it, and have hot water bottles that you know how to fill safely, then you can be sure that you will have a warm bed no matter what happens. If you already know that this is possible and ready to implement, you can focus on more intermediate stop-gaps like solar, wind, battery backups etc. without worrying that you have nothing in place should the power go out. Expand this as far as you want. Lowest tech first, then fill in the middle with redundancies.
Another way a homesteader can avoid cascading failures is to keep things as simple as they can. KIS (Keep It Simple: is often a very worthy design principal).
I ran into this a few years ago. I have my back-up generator which is a 55 HP diesel engine going into a 20 KW generator. I was going to plumb the radiator lines into my radiant floor heating system so that while it was running, it would take the waste mechanical heat of the engine and use it to heat my house. It made sense as I was burning fuel that made heat that was going to waste. It would be cogeneration at its best... a stacking function....
But then I thought about it. It would have been complex to plumb the coolant lines to do that when all I really needed to do was plug in electric heaters in the house. My generator consumes roughly the same amount of fuel no matter if I am consuming 10 KW or 20 KW. Since I have plenty of extra killowatts to use, it only made sense. Everything was wired already, and my generator was already making electricity.
Keeping things simple can go a long way towards longevity.
Preparedness is like accountability: you need to have some of it, but if you overdo it you are wasting more energies than you are saving.
When designing for failure, first thing is to evaluate if the element is worth to consider. A failing pipeline can be very damaging, but the lighting system of the house not so much. Anything with fire or water is a must in home safety. Drink and food security. Accesibility, being able to escape the house in case of need. Clothing? TV? Not so much.
But I think the real point from OP is that when designing for failure, you are expecting that there are many other systems working, which in real emergencies, might not be the case. That's why collapses happen. The usual backups for failures aren't working either. Then one element of the system fails and a cascade of failures follow.
I'd say that collapses cannot be avoided, there will always be some conditions we didn't plan for. So, the interesting question for me is: what can you do to survive a collapse?
A possible option is to have a backup "system". For example, if the domotic system fails, then fall back to manual. If capitalism fails, fall back to feudalism. The old systems were left behind for a reason, but if the newer one doesn't work, that'd be an option.
Another option is to be creative and pour new elements to the system until a new balance is reached. For example, we may adapt to use solar panels without batteries, we won't be enjoying the same service, but at least we would have "some" electricity, and should make good use of it when available. That's still better than having no electricity at all. Or we could change completely the way we tax people: imagine how a unique tax on land property could change society. These things are not possible today, but during a collapse process new ideas can make their way.