Thunder made some good points. Muscle memory is the key to being effective in a stressful situation. If we expect to be accurate and efficient in a real life situation, we have to train until it is second nature and we are not having to think about how to clear a jam, reload or about shooting techniques.
I also believe that it is a good idea to try and keep the same caliber weapons. I go with 9mm for handguns but a variety of calibers for rifles depending on the rifle. If I am just practicing movements or techniques, I like an M@P AR22 to save on ammo costs.
I am not a big fan of Mozambique Drills just for the fact that I don’t believe if we have double tapped at center mass, there is a need for a head shot. The military never teaches a headshot, but always center mass. To me, the head shot is a waste of time and energy.