I always buy at least 1/8 to 1/4 yard extra cut then I bring it home and rip it to get the absolute straight of grain. I would rather lose 1/2 inch (1/4" each end) trimming after being ripped than sometimes about 1/4 yd. when it is cut and most people, even in quilt shops cannot cut a straight line without a ruler. However, in all of my local quilt shops, they do use a ruler when cutting.