Keep in mind, that while we might call them "blocks" they are just fabric with seams. You can cut them into strips, resew them, and treat them as jelly rolls if you want. Doing a rail fence type thing with a consistent solid or two can help tie things together.
I find it hard to cut down my own blocks, but I have no such compunctions when I find a set of blocks in the thrift store or someone's UFO pile.
One of the ladies in my sewing group makes a variety of bags as gifts and for various organizations -- she's great about using just a single block (or a couple) with her own fabrics.