I know one of those types. After a bore-scope investigation, he told me that my original Winchester 94 in 3240 was only fit for a display cabinet, not for shooting. But my WIN94 doesn't understand Germanand therefore continues to shoot as well as I can point it (well OK, perhaps that's not so good any more).
So in which competitions does your friend participate, and how well does he place? I'm not being sarcastic, but there are some shooters who are so wrapped up in load fiddling, that they lose contact with actual shooting performance. I have a 6mm BR that will produce an 0.2 MOA group at 100 meters. Unfortunately, my PWF is larger than that. In other words, I am the limiting factor, and even if the rifle could produce 0.1MOA mounted on a lead sledge, that would hardly produce any visible improvement in my scores.
Twice as much time spent in practice under competition conditions would help me more than twice as many steps in producing "perfect" ammo. There is an old saying " a bad workman always blames his tools". Certainly, some spend more time optimizing their tools that actually learning to use them to best effect. OK, I'm old-fashioned.
Getting back to the 30-06 (or .308 for more modern types), I think it is not correct to conflate the Garand with its .308 successor, as the distance between the muzzle and the gas port on the Garand is much shorter than on the M1A. So where the Garand op-rod receives a short "puff", the MIA gets a comparatively "slow blow". Still, I appreciate the warning and will seriously consider N135 - which, by the way, is the fastest powder in the Vihtavuori loading tables for 30-06 with 130gn or heavier bullets.