Folks shooting 3 shots per test group may want to check out:
It's based on the age-old engineering and statistics standard of "If you don't get the same number each time you measure something, your ruler's either broken or not being used correctly."
Best example in the shooting sports is when someone shoots four 5-shot groups, measures the extreme spread of each, then averages them. The answer they get's a lot smaller than if all 20 shots were fired in a single group. And that 20-shot group's larger than the biggest 5-shot one.
No wonder there's several thousand "favorite" loads for a given cartridge and bullet. The popular reason is "Every barrel's different." I'm convinced there's a much, much greater spread in variables elsewhere.
Just food for thought.........