Hi Eric. If you stay open in every situation the awareness of your corners/shape is the mainpart of your development. In my opinion it depends on your individual set-up. So experimentation with the leadpipe in the most efficient way should show you the correct movement. Resonant sound and a minimum amount of corner/shape movement (efficiency) are the goals. The feeling/awareness of your own unique shapemovement is much more useful than a video showing others doing their unique movement. Vertical tightening is no good idea!
I would like to hear Greg about this topic as well.
Hope it helps