Waste was when I was working on my first set of blocks for my daughter's bed-sized quilt and I cut eight 12" repeats, but only used 6.5" squares out of that 12".
Had I done this before, or been thinking harder, I would have realized that I needed to do this two more times, and I would just have cut 24", and gotten 3 rows of 6.5" squares out of it.
But you see I needed a lot of blocks because it was for a large quilt. If I was just doing a wallhanging or a tabletopper that would have been different.