Long ago, I learned when racing motorcycles at the track (road racing, paved): "learn the fundamentals, make them second nature. Speed will come. Trying the latter before the former will lead to woe."
Bikes are like firearms in a few ways, one being that clowning around can cause injury, property damage, and death. Draw what you will from the analogy, those who ride and shoot might agree with me....though hopefully you don't ride and shoot at the same time!
So, I've taken various combatant courses from people who are *not* clowns, mostly run by Operators, current or ex LEO, and ex military and/or reserves. I figured, correctly, on Day 1 to open ears and shut mouth. Thus, I've learned reasonably clever technique over the years, practised enough to become second nature. And, speed and accuracy have improved, though that was pointed out to me by others. I'm no Rob Leatham, to be clear, but put lead down range and hit the mark often enough. Confidence and not being rattled...zen calm under stress... are 90% of the battle.
And yes, some days I'm not in the zone. I don't shoot very often, maybe quarterly to keep the skills from getting rusty. When I go with friends who shoot even less, I sometimes stop (both, all) of us/them when I sense fatigue setting in. It's a bit stressful to shoot 45acp, 9mm, and similar box after box. One might surmise there is a point of diminishing return, but I'll leave that to the professional instructors who see many students per year.
For me, the groups open and I start to slightly flinch if I'm tiring, that's my first and last clue. So, I pack up and go home: the range will still be there tomorrow. For me, 2-3 boxes of 45ACP are sufficient for most sessions, unless I'm ad hoc teaching new or less-experienced shooters (girlfriends, buddies, etc.)