Mike Fedora told me to tuck the chin down. I don't remember the chin to sholder message and I can't find my notes from my first lesson with him but I remember him tilting my head down so that my aiming eye was closer to the arrow and the "gap" was smaller. When I start sparying arrows, I focus on this, hold at full draw a little longer, lining it up and I then shoot tighter groups. This, plus practice works for me. Mike had my chest face the target a little too much which shortened my draw length. If I keep my feet at 45 degrees to the target like I think he said and pivot my sholders 90 degrees to the target, like the clock diagram shows, it all works great.