I was taught that a full binding will last longer and if a quilt is to be judged it is a big no no if the binding is not full. And I like the look. That said, I stitch the binding onto the back with a walking foot before trimming. The excess provides a stable area for the entire walking foot to rest on. Then when I trim I try leaving a little more for a short distance & turn to the front to be sure I have enough to make it full but not so much it makes it difficult to hand stitch to the back. If there is a little to much in some places, I can always trim a little away before stitching. I enjoy making hand finished binding