The strongest players in my area pretty much all have somewhat poor PSRs and mechanics, at least in comparison to what's textbook. They also play very fast and hit the balls too hard with somewhat spastic strokes. But they're (mostly) accurate, and I suspect that trying to slow down or change their stances/strokes would actually hurt their games because they've been playing like that for so long.
Meanwhile, I have pretty good mechanics, good PSR--everything looks fairly textbook--but I'm not on their level because I simply don't have nearly as many hours invested in the game as them.
I think that no matter how good your setup is, it takes a ton of hours, and likely a full period of your life with near 100% immersion in pool, to obtain the confidence required to play at a high level consistently. Where even the somewhat difficult shots are assumed to be pocketed, regardless of the pressure. Because you've done it enough times that your brain can relax a bit and just the motion happen without subtle interference caused by the fear of missing.
