Watering is a place where I actually feel like permaculture principles should be really carefully contextualized. If you don't have access to any water, then definitely applying principles that mean you don't have to water are great. Mulch, in our Mediterranean climate is a game-changer, as is shading the soil, and encouraging self-seeding.
My perspective is to do what gets you a yield that you and your family will eat, and for beginners like me, improving the soil can be a full time job. I have, in our 4 years of farming, been able to develop a strain of Cape Gooseberry that needs no water whatsoever (ok, not so much develop it as plant a bunch and leave them and see what survived and then use the seed from those guys), and I'm extraordinarily proud of my achievement. I have also been able to time potato planting so that if I plant around now, I can not water at all and harvest in Nov (though I get a better yield if I water in Oct/Nov). So I think about water, particularly for the areas of our farm where we don't really want to put in expensive irrigation systems, or strain the capacity of our wellpoint by using it to pump water to the very end of our property.
At the same time:
I started farming in a period of extreme drought (EXTREME) in super sandy soil and I thought I could make plants and trees stronger and survive by doing the deep (well, sortof deep- I was being really careful with watering) 1/week watering thing, and it was a really bad misinterpretation of permaculture. I lost a lot of trees, encouraged Cape dune mole rats to eat my trees (watering deeply once a week collapsed their tunnels which made them come up and enjoy a tasty snack of my tree or bush)
I think for me permaculture is partly about trying to make things have more than one use (including supplying as many of your needs as possible), to make your landscape increasingly resilient in a way that is gentle and supportive of the land you have stewardship of, and to make the best possible use of that land.
That has meant, in our annual garden, growing some water-intense things like strawberries because I want to be able to eat them and they are well-suited to our climate in some ways... actually watering a lot of stuff in our annual garden almost daily because I'm still a beginner and I can't gauge plant stress terribly well. As the soil improves, my need to water declines. I figure I am always using less water than commercial farmers, and my primary goal is to get a yield without any commercial products. But I would not tell a beginner gardener to try dry-land farming, or to really think about trying to water less in our climate and soil. I would rather suggest starting by thinking in terms of deep mulch, planting on either side of hugels and berms, and just learning gradually what your trees and plants need. It is too discouraging to be a crappy farmer with tiny wilted plants, tasty as they may be, if you (I) have never grown the good stuff. Now, in year 4, that I've grown at least some good stuff, and the soil is a lot better at holding water, I can experiment with water -- my goal is to irrigate for 2 weeks less than the previous year, but it's not a hard and fast rule and depends a lot on when the winter rain starts and ends. So stopped irrigating the last week of April this year, and hopefully will only start up again the last week of September...