I buy enough to make sure that I don't run out of what I am working on. If I need 1`-1/2 yds for binding I buy two yards, If I need 3 yards for backing I'll get four yards because I just may decide to do the binding in the color of the backing. I really don't buy more than I need. Plus a little more in case of a mistake. Which, of course, we have all been known to do one time or another........I am mostly another!!!!!!! This way I have all my bases covered. Edie