Which means exactly how much change in POI at 55, exactly how many millimetres.
Used to weigh them, size them and lube them. All makes very little difference in reality.
When you are doing half inch groups and shooting at 40mm targets, and you miss, you have calculated the wind wrong not the range, generally.
I used to shoot at that level too and same grade in NEFTA as you Chris, but for me it was fun, never took it that serious (no money involved, apart from getting sponsored and given free kit). Not for a while though, life gets in the way.
Think we used to attend maybe 5 shoots in a season as some clubs just weren't worth the travelling to. Turn up, embarrass reigning and ex world champs and go home.
I think though if it works for YOU, then carry on. Placebo effect and all that. I would place practicing your shooting technique to constantly achieve tight groups and reading the wind, over any pellet TLC.
My Crossman Prems 7.9 never varied as much as the stated .7Gn, or move in the wind like the JSBs, so maybe look at different pellets, but like I have said in past just because a champ uses a particular make rifle, pellet or weighs them does not mean copying him it will work for you.