In
theory it sounds good........
Most dreams last only a few minutes - occasionally you might get a really interesting one that will last up to 15 or 20 minutes IF you are able to take control. So what you might end up with, IF you are able to program precisely enough, is a series of dream "practices". BUT sometimes we are dreaming up to three or four (even more) dreams at the same time, and that is why things seem so jumbled to us. To achieve the kind of clearness of purpose needed to do four hours of steady dreaming would mean you'd probably be past the need of dreaming about doing it anyways.
I remember when I was a kid doing a lot of piano concerts, I'd end up dreaming about the concerts the night before - usually ended up with my teacher (an Ursuline Nun, in long flowing black robes and tradition head-gear) chasing me off the stage with her pointer. Not much practising there....
Cheers!
Unis
