One quilting friend buys only the exact amounts of fabric she needs for a project. When she gets into trouble with a wrong cut or shrinkage or a change of plans, I'm closer than the FS. I always seem to have just what she needs. Since I know her so well, and she shows me everything she does, I can be prepared for her. If she knows I make a special stash for her, she is not letting on.
I on the other hand can't go into or past a shop with out finding fabric I can't live without!
peace