RE: the wall
I sometimes have trouble with creeping or letting my bow arm soften which is very bad for accuracy. When I catch myself doing that I will pull tight into the wall, but I don't pull past the wall. Thatuses uptoo much energy for tournement shooting. Also, pulling past the wall would create a lot of muscle tension that is usually the source of poor accuracy. He may be able to do it, but I think that it is not practical for almost everyone else.
The better tournement archers that I know (I'm not one of them - - yet) strive to find the most relaxed execution possible.
I think that you may have misunderstood what he was saying.