I don't have a monster stash but it's nice sized. I do buy fabrics just because I love them and know I want to use them in a future project. When I buy just for stash I buy anywhere from fat quarters up to 10 yards depending on what the likely use is. For blenders and designs where I'm likely to use several of one color I buy up to 1 yard lengths. For fabrics that I think will end up being a single supporting player I buy 2 or 3 yards. For focus fabrics I usually get 4 yards. If I think it's a great background neutral I buy anything from a 1/6th yard roll to 6 yards. For backing fabrics I almost always buy 8 yards. That way it'll work for the back of anything up to a queen size quilt. I don't buy a lot of fabric often though. I usually only buy big amounts of fabric two or three times a year at the most.