(This is a bit of a clickbait title because people are different.)
What is the main reason shooters keep missing what they're shooting at? How can we help them overcome the issue?
1. Trigger mechanics: trigger pull moves sights off target
2a. Recoil control: arms move sights off target in an attempt to control recoil
2b. Recoil timing: you attempt to time the recoil cycle of the gun, but press the trigger at the wrong time.
3a. Transition timing: you pull off the target before the gun is finished shooting it, or shoot before the gun has arrived on target
3b. Transition damping: your transition wasn't 'critically damped', and you overshoot the target.
4a. Sight alignment: sights misaligned
4b. Sight placement: sights aligned but aimed wrong (usually looking at the wrong place on the target)
5. Vision: focus or eye dominance. Looking at the sights through the wrong eye.
Other things?