I've only had top loading machines; our new one doesn't have a central agitator, but I still get the fraying (it doesn't seem to matter what setting I use). My preference is to zig zag my edges before washing, but if I'm in a hurry or have quite a few pieces to wash, I just clip the edges in a few places; this at least stops the fraying from going all the way across the fabric, so the frays don't cause tangling and excessive wrinkling.