The rulers is almost foolproof. You do not have precision cut strips (just 1 1/2 inches or wider). You don't even measure the length of the strips. Just sew them on and then square up the block. The block doesn't ever get wonky. I used scraps of fabric that I didn't think would ever find their way into a quilt.
Thanks for the quilting suggestions. I really value your input. I'm not very good at this part of quilting, and it is so devastating to have a quilt half done and realize I made a bad choice.