I think what the poster was saying is that there's a difference between a reliable 3 shot group accuracy, i.e groups center to the same poi each time, and someone who determines reliable accuracy based on a few 3 shot groups.
An example would be you shoot several 3-shot groups; while each group may vary in size a little, the group center remains roughly the same, so that if you shoot a 20 shot aggregate group, you may see the aggregate group size get a little bigger than your 3-shot sample, but for the most part it still stays centered at your original poa.
That's in contrast to someone who goes out and shoots 3-shot groups, and while their group size might vary a little from group to group, the group center moves around the poa. In the latter, an aggregate group may end up being much larger than expected, and may not end up centered on the original zero of the scope. Because they use too small a sample size to zero the scope for the inherent accuracy of that rifle. More accurate rifles need fewer shots to zero poa to poi, less accurate rifles need higher shot counts. That's the whole point of calling out low sample sizes, is that some rifles simply don't shoot the smaller aggregate group sizes that the owner thinks they do. Meaning, that .5 moa rifle, might actually be a 1.0 moa rifle over many shots, and as it actually counts in the field on an animal.
I have a buddy that is convinced his factory 22-250 is tack driver, because a long time ago, he snuck out onto the 600 line and put 4 shots into a 3" group. Since then he hasn't been able to repeat that accuracy at distance and it drives him bonkers. At 300 yd, his 3-4 shot group centers randomly move around the target dot, though each individual group is usually .3-.7 moa, occasionally 1.0+ moa. If you overlay his groups, they make a neat 1.5-ish moa circle. Sadly, because the group poi's move around the dot, he deemed it must be a bad scope, so the scope got sent back to XXX for repair, and they found no fault, and he wasn't happy. He swore to never buy another XXX brand scope. Changed the rings, same thing. He simply refuses to accept that it's a 1.5 moa rifle at distance, and he's judging the thing based on too small a sample. Just plain madness.
But the point is that people can do the same nonsense with tuners if they shoot small sample sizes and maybe refuse to accept that their rifle isn't as accurate and precise as they think it is.
This is a bit of an extreme example, but I have a lever gun that I've been trying to get LVR powder to work. I have no illusions that this is some sort of tack driver. When I was zeroing at 100, this is what I got shooting 3-shot groups. The 3-shot groups were actually shot over several different sessions, cold barrel each shot, all within maybe a 10* temp range, loads temp soaked for a least an hour. I have the aggregate group marked with green sharpie. The average 3-shot group is probably 2", but the aggregate is around 3.5"-4.0". 1) The scope is good. 2) It prints the same aggregate with a clean bore. 3) And I finally abandoned this powder.
View attachment 535399