All the above is fine as long as one has a consistent mount. If they don't most of the above will not amount to much.
I can make most any shotgun fit me when I'm consciously mounting it or shooting pre-mounted. When I'm not is when the truth is revealed.
Part of a gun fit is shooting at targets. Mounting one in the store it may seem right, but there is a better than even chance it isn't.
See many go to the pattern board and quickly bring the gun up and slap it into the face then slap the trigger. Most of the newer shooters are quick, but not smooth. The experienced ones are smooth, but not necessarily all that quick.
I hear many say slap the trigger hard. I'm not for anything that moves my head around. Either in the mount or hitting the trigger. I can't think of any eye/hand game where bouncing your head around is an advantage.
