Rebs, shoot all of the same load in one group. That'll show what it does. It'll have a composite of five 4-shot groups, four 5-shot groups, two 10 shot groups, six 3-shot groups one 15-shot and one 5-shot or any other combination you care to use. They don't matter. It's where all 20 shots go and all of them will tell you where about 80% of all your fired shots with that load will go. Shoot 100 shots per group and you'll know where abouit 95% percent of all the shots go. Military arsenals shoot 200 or more shots per test group; they want near 100% assurance of where all the shots will go.
5-shot groups only show what about half the fired bullets will do.