I cut my fabric for borders as LOF if at all possible. I don't like them stretchy. When I sew them on, I cut to length, then I do pin at the half, then each quarter point. Then I pin in the center of the spaces between those two pins. If I see that the bottom is pulling too much, I hold the two fabrics together and make the feed dogs pull evenly. None of my sewing machines have an even feed foot. I have never had the borders stretch and wave when I do it like this. I do the same procedure for WOF cuts, but am not as successful. I like the idea of stay stitching the fabric if the borders are cut WOF. I will try that the next time.