For a long time, I'd often buy a couple of yards of fabrics that I really liked, with no specific purpose in mind. When I made quilts, whatever was left got tossed in a basket. However, I love scrappy quilts (and fortunately for me, they're popular right now). That meant that either my quilts had more of a given fabric than I wanted, or it got used in many projects before it was gone.
It's all good - now I have a decent sized, but manageable, stash. New purchases are much more likely to be in the 1/2 yard range, unless it's a great neutral. Always on the lookout for those, I'll go with a 1 - 1 1/2 yards of them.