I think it's official target anxiety. Put up a target with the official sticker on it and suddenly my arm gets tired and any attempt to increase the pressure on the trigger results in my gun shaking like a dog trying to pass a peach pit.
I know it's all mental.
I was so disgusted with my caplock score that I didn't even practice with my flintlock pistol, just posted my targets and got it over with, and I shot a 79 on the 50 yard target, the high score of the shoot for that match.
During the October shoot, there is a match called the longhunter match, 15 shots at three critters hiding in a tree at 25 yards (the nightmare target), in one 30 minute relay. I often enter that match not serious but just to loosen up. You don't have time to aim and aim and aim. You gotta get up there and shoot and then reload.
The time pressure makes me get up there and get the shot done and I usually shoot surprisingly well, boosting my confidence.