Have you ever bought a yard of fabric that had been cut for you and taken it home only to find it to be terribly crooked? Snip it, tear it and you will find that you really don't have a yard of fabric. I don't know how many half yards I have had cut that end up maybe only 15-16 full inches wide across the 42+ inches. My mother was a terrific seamstress. She always tore her fabric to get it straight before she cut out a pattern. That's what they did in the "olden" days.