I've picked the sashing material for a set of blocks, and I'm cutting those pieces out now. I don't like to cut width of fabric strips for the setting pieces because it isn't usually an efficient use of fabric . In most cases you can only get three or so pieces out of the strip, leaving odd little bits at the end, and I don't like wrestling large pieces of fabric around, nor do I want to press a big length of fabric.
I cut 3 1/2" strips from the piece and ended up with no leftovers at all.
Then I trimmed each of these to the size I needed. There may be a slight bit of waste with the extra inch I've cut, but this is worth it to me for the convenience. And if you square up the width of fabric cuts you can lose a few inches anyway. This method suits me fine.
It feels good to be making decisions about these projects and getting fabric cut ready for sewing.