I mostly backpack in cool/cold weather so usually I take three layers. Since I mix and match those depending conditions you could say I don't bring a change of clothes when I'm wearing all of what I brought, or you could say I have one or more changes when I'm only wearing one layer.

As far as rain goes, I try to have one layer packed to stay dry at all times. Generally that's a pair of fleece pants and shirt when I'm hiking, but it can vary.

In the past few years I have cut back a lot on the weight of the clothes I bring, and I wear everything I bring now too. I don't think I could go much lighter there without spending a lot or being cold.

I'm always looking for a deal though. My nylon zip-offs are getting pretty old and beat up, and I can't find those on the shelves of any stores around here anymore. Don't know what I'm going to do about that