Yeah, partly because that's about what I've noted when firing 3-shot groups with a rifle, then marking the group and shooting another two rounds.
The statistics guy I corresponded with said the long time American Rifleman standard of five, 5-shot groups was pretty darn good for predicting a rifle/load's consistent accuracy--but also that when using modern computer programs he'd found 6-shot groups were a little better.
It all depends on what dependable degree of accuracy somebody desires. Obviously that would be very different for the average deer hunter--or even a traveling hunter who's after elk, or African plains game--than a target or small-varmint shooter.
