My Mom was the best seamstress I have ever seen...she would make a very slight cut in the edge of the fabric, carefully separate out one thread, and cut along that thread over the width of the fabric. Her seams were always as straight as an arrow and her quilts were lovely as well. So I'm guessing that her way (as usual!) WAS the best way...at least I can't argue with success. And no, I don't do it that way unless I'm making an heirloom quilt!