Taking a step back, some might not like organizing their material, and rely on just search tools such as Spotlight with MacOSX. That’s just fine, as well.
I’m just now reading David Weinberger’s interesting book Everything is Miscellaneous, where he points out the new way of looking at information that Internet is defining, in other words there are multiple ways to find information, using tags, search urls, listings, categories, and so on.
My point is that it’s somewhat good to rely on some mind of organization. The least I want is to sit and hunt for material when suddenly the creative spirit kicks in. But I do think that creating organizational models is very personal, so the more you put in from your own side, the better chance you will use it long term.
One last note about projects. I always, always try to render out temporary material. This way if I’m not sure what a folder contains, I could quickly play the rendered file and know what the folder contains.