If you are making the backing from regular yardage, it probably is best to ask the long Armer how she wants it. On my 12-foot frame, I can do a queen-sized quilt but may need to think about how I will load a king sized one. I usually do over-all designs so sometimes I will load a quilt sideways as I will not have to advance the quilt as much. I have a 26-inch machine so maybe can do the quilt with only 3-4 advances. Anyway, you want to be able to have the backing seams, so they are Parallel to the rollers, so the seams go the entire length. If you have the seams on the backing so they are perpendicular to the rollers, that seam will build up a ridge as the quilt is advanced making it probable that you will get a wrinkle in the quilt.