As I get older, I find it gets harder to manage large chunks of fabric. So if I am using 42-44 inch yardage to make a quilt back, I cut the fabric the length I need, leaving the selvages on. Then I line up the selvages and stitch my seam about 1.5 inches in. Then I take my scissors and trim the selvages off. I find this easier then trying to the trim the selvages straight with a long pice of fabric as my cutting table is only six feet long and is the basement with the unfinished concrete floor. I leave the edge selvages on and find when I load the quilt, it is easy to make sure it goes on straight, these selvages get cut off when I trim the backing after done quilting.