I don't hang mine in bundles because I have no where to hang them. I would think what you are proposing would work for you.
I put my herbs on trays in my hot machine room/laundry room on top of the washer/dryer. I turn them when I think about it and when dried sufficiently I cut them into appropriate size and let them dry some more. When I put them in jars I leave the lid off for a while to make sure they are very dry before closing the lid.
Invasive plants are Earth's way of insisting we notice her medicines. Stephen Herrod Buhner
Everyone learns what works by learning what doesn't work. Stephen Herrod Buhner
Bundles work for me, because it takes approximately the same amount of time to hang up a handful of herbs in a bundle, as it does to hang a single stem. A bundle might hold 20 stems, so bundling saves labor. I really like hanging things to dry because they get great air circulation.
Hanging herbs is just one option available to me. I might also dry in a dehydrator, or by laying out on flat surfaces or screens.
Sometimes it does depend on the location and also how fragile the herb is. I had some bad results using a dehydrator to quick dry herbs. A lot of the volatile essence was lost. Bundles do not work here in the summer because Long Island is humid as a steam bath! Using a folding laundry rack and simply putting the stems over at a fork works, or spreading them on newspaper near the hot water heater also works.
Bundles work well and are quick in the winter when it is dryer here.
Good luck with your herbs! Find what works for you. I don't think there are really any hard and fast rules except those introduced by nature, like humidity makes things mold!
The real world is bizarre enough for me...Blue Oyster Cult
Bundles worked well for us in drier climates. As has been mentioned, it saves time to quickly gather herbs into larger bundles then tie them up, rather than tying up many more single stems. Also, being upside down allowed gravity to straighten the herbs, allowing them not to flatten from laying on a horizontal surface while drying, making some of them easier to harvest when it came time to using the dried herbs. In a more humid climate, we've spread them out on paper towels to dry, reusing the paper towels when finished.
As you have probably gathered from the previous posts, there are many ways and each climate has a best method.
If you are going to be drying herbs indoors (as in inside your home) and if you have air conditioning, then bundles will work because the humidity is reduced by the air conditioning.
If you are drying outdoors in high humidity but also have good air flow, then the tobacco barn type drying will work great too, the air flow reduces the dampness and the bundles slow the drying process so all volatile oils remain where they are supposed to be.
If you are in high humidity, stagnate air type areas (low air flows) then you might be better off with single stem or just a few stems to a bundle.
In most "tropical" areas (lots of heat, high humidity, low air flow/ no winds) then you can get great results with a solar dehydrator, incorporating light color fabric(cotton) sheets between layers will work nicely to get great results with a dehydrator.
Bundles are for speed and ease, plus almost no one needs just one stem at a time. My wife uses about 4 stems per recipe she is making.
Bundles have been traditional as the method of drying herbs since at least the time of the ancient Greeks.
The best method for drying herbs is the method that works best for you.
I wrote a blog on drying herbs that you can find here: http://dreamingabeautifulworld.blogspot.com/2013/01/drying-storing-herbs.html It is too long to post all of it, but basically it goes over choosing appropriate drying rooms and what makes a good drying room such as a clean attic with good air ventilation. I also cover drying herbs outside and what hazards to be aware of such as night time moisture, and insects. Then I go through the different parts of herbs and how each is dried, which includes the aerial parts, roots, seeds, flowers and fruits. Next it covers how to store all these different parts of the herb for longevity.
May You Walk in Beauty,
Sharol Tilgner ND
Sharol's books available at website