Considering that these pre-cuts get shipped several times before they get into the quilter's sewing room, it definitely helps prevent fraying. I know with the Moda precuts, they are cut in Korea, shipped to the Moda warehouse in Dallas, then to me, then to you. They can really take a beating with all that traveling and no telling how many times they get handled in between especailly if they are on a shelf in a LQS. If you cut them yourself, by all means cut them straight if that's what you prefer.