I did not know this when I made an Amish type quilt with a lot of black fabrics. After I finished it I realized that the blacks were all different shades. But when I looked at it the next time, I saw that the different shades gave it a little "life" to it. Sure, not like a traditional Amish quilt, but I am quite pleased with the outcome. Buying the same fabric from the same mfg will also have shade differences, but again I like the slight variation. It's hardly noticeable if it is a print, but the subtle change really peps up the quilt. In another quilt, I needed 9 different shades of solid grey, 3 light, 3 mediums, 3 darks. It was a matching nightmare to get them all to play together well.