I can't think of a reason to back stitch in quilting, but as I read the OP, this memory came up.....once on f&p, when it was really that, Liz showed how she did a backstitch. Started her seam about three stitches from edge aiming toward that edge, put in those three stitches..at that point at end of pieces, raised pressure foot, spun pieces around so it was going in the " right" direction for sewing that seam, stitched over those beginning stitches and continued to finish that seam. I have actually done that on some projects other than quilting, as sometimes using the backstitch button causes a bit of lumpiness....... And I think I have seen Kaye wood do an end seam where you stitch to the end, pivot and stitch back into seam a few stitches to lock the seam