I always tend to buy a little more fabric than I need, so that if I make a wrong cut and have to make a new block, there will be enough fabric to do that. If you have so many extra blocks, why not make a sampler quilt - even if you don't use the quilt it will always make a good charity quilt. I like to think of having extra fabric a cushion - like right now, we had to downsize to a small apartment, so space was limited, however I drew a line in the sand when my family wanted me to get rid of more fabric. Now I'm making quilts from my stash and I have the fabric available, although from time to time I do need to pick up something to finish a quilt, the majority are from my stash. Shopping in my stash is almost like going to the fabric store, although going to a fabric store is a little more fun.