Just like any competition, the mental part is at least 50%. You can hit your target all day long, eyes closed. Add some pressure and a distraction or two and you can't focus on the task at hand. This is problem for the very best of every sport. Think Tiger Woods. He didn't get less skillful. The distractions destroyed him. There's too many stories of athletically capable people not getting beyond the mental and fail professionally. If it was an easy answer, it wouldn't be a problem at the highest levels. If you figure it out, bottle that shit and make a fortune. Other than that, try meditation. Removing all thoughts from your head except the task at hand.
I get where you're coming from but if I'm being honest with myself; I'm not going to place high enough for it to matter if an RO misses one or two points. I haven't tried this at a major PRS event yet like the SDSC and to be honest I'll probably write mine down there so I can compare where I'm at from last year. But as far as one day matches, I stopped writing my stuff down I'd rather spend that time focusing on the next stage or helping some of the new guys figure out how to shoot a stage.Not sure I would do that. I always keep track so I know and to keep the score keeper honest. I like to know and be able to look back if there is a scoring issue and know what I did. Not to harp on a bad stage but just to know.