The closest thing to competition I do is the 30 yard challenge. I am not great but I have shot a few 200s, the goal. I've tried most of those steps but I did not find any difference in my scores. I find checking head size variation in a tin of pellets is useful when they do not seem to shoot well. Often I find high variability in the head size. But when I try sorting that tin it doesn't "fix it". I think the head size variability is not the real issue, it is something about how the pellets were formed. I find enough "junk" in empty tins of Crosman pellets to make me think they could use a wash. But I doubt it would turn them into top quality target pellets. My 200s have been with pellets straight from the tin and normally through a magazine. I might have used a single pellet loader on one of the most recent. I prefer printed magazines, however, I think there is less chance of pellet damage.
What does make a noticable difference is finding a pellet your gun "likes". For instance my P35-22 likes H&N Baracuda 21 grain Match pellets and I shot a 200 with this gun and pellet. But it required a lot of attempts, dozens. This year I tried AEA 21.9 grain pellets and the second target I shot with them was a 200. I've shot a bunch of lower scores now but the gun likes them better than the H&Ns. I don't know if they are made better or it's just a gun preference thing. But I'm happy I tried the AEA pellets. The AEA 18.3 grain is my Bullsharks favorite but my Caiman still likes the H&N 18 grain Baracudas better. That makes me think it is probably a gun preference thing. This is with the same tune of the gun for both pellets. The weights are similar and while I've tried small changes to make a pellet shoot better once I have a good tune a minor change in the pellet doesn't seem to mean I need a new tune.
Maybe if I shot better or shot at longer range I would see a benefit in some of the pellet preparation steps. But I think the most important step is still finding the best pellet for your gun.