I have learned that having a big stash is not always a good thing. Before I retired I tried to sort of build a stash & suggested (to those who would listen to me) that they do the same thing....build stash while you can. Now I'm re-thinking myself & have to reverse my opinion on that. I think having a small stash is better.
I've also learned that when I start making several mistakes in a short period of time it's time to stop quilting & pick it up on another day. It tells me that I'm tired & not paying attention & I make more mistakes when I'm tired.