I have little doubt that plenty of "internet rounding" is applied to a lot of posted groups... (I think we had a guy in the rifle section shooting 2" at 200 yards with an "AK and regular ball ammo" over the weekend. That one gave me a chuckle, as do some others) But even for people who aren't necessarily completely making something up, omitting information via only posting the one best 3 shot group of the day, as plenty of people readily admit they do, is still misleading. One three shot group means nothing. I've been at the range and happened to have three or four consecutive shots land into an an area the size of a dime or less. Yeah, sure it was fun while it lasted and I'm sure there are plenty of people who would have stopped right there and posted that group on the internet saying their milspec AR shoots 1/4" groups when "I do my part"!!! When it becomes a 3" group after the 5th shot, well... what is a better description of the average dispersion, 1/4" or 3"?
For me personally, when I have a load that I think I like, I shoot 10 to 20 into a group, before, to me, it "shoots x.x" with this ammo, bench setup, conditions, etc".