Myself, in my younger days I was an accomplished rifleman and hand gunner, perfect practice made perfect. However as I aged and genetics kicked in (neuro -muscular degeneration) it’s slowly robbed my abilities.
I still shoot, but no longer compete, instead of being rock solid in form you can now see a bit of tremble in my front sight.
I believe the key to a "good shooter" is ability to concentrate on task, control your respiratory system, and repeat action over and over again. You need to be in relative descent shape, have good eyesight, and have some descent equipment.