I purchase yardage of black or white when I have a 60% coupon or a good sale on Kona black or white cotton. Then when I cut that yardage I keep all the leftover pieces (including scraps) in a marked baggie so I can use them in another project. In the pass I was working on a quilt with a black background and somehow I ended up with blocks from different dye lots. Want to avoid that happening in the future.