They say you should learn from your mistakes or you are doomed to repeat them. I say we should learn from our performances. For me every major performance is a learning experience. There is always a line that can be made better, a joke that could be told differently, a method that can be tweaked, etc.
I'm not saying that every time you perform you should walk away with something. That card trick you did for that waitress may not be a lightbulb type moment... but it could be.
Over the years I have learned from and played upon my mistakes as well. You can't ignore the tiny details because it is those things that make up the big picture.
So pay attention to your shows lest you are doomed to repeat them...