I partially agree with you in using one waterblock and one IHS may not represent ideal contact, and may not be representative of all mounts, and there is certainly some error in that and will be variation in pressure.

But you grossly understate the error of using forum feedback as a legitimate means of testing tim. Are you suggesting 10C 14C 20C differences actually occur with different tims? I can compare IC7 to toothpaste and not see that much of an effect.

Many are eyeballing core temps after a fresh install where internal air has cooled which will cause temps to be a few C cooler, and some either had mounted with no tim before or are exaggerating or are people pleasing or just plain bsing, and some may have accurate testing equipment, but without sorting out what, I cant make any conclusions for it, other than I would rule out using forum feedback as reliable tim testing.

Now if you want to personally test 5-10 different cpus/blocks/setups, and show difference of one versus many using proper measurement equipment, I would like to see that.