My stash is in a 6' cabinet. I keep it very organized. Flannel, holiday and pre-cut batting on the bottom. Next shelf up is larger pieces; 4 yrds or more on their sides. Next shelf looks like a book shelf (fabrics folded vertically). Top shelf is 2 1/2" strips (leftovers from past projects), fat quarters and pieces less than 1 yard.
I do find surprises that I forgot that I had. However, I have yet to buy a double. If it doesn't fit, I need to use up some of the stash before I buy more. I usually have extra batting from quilts which I cut up into 8" squares to be used in a rag quilt. If I want to make fast space, then I make a rag quilt.