Geez Clark, you never sat at the bench next to me.
Truth is, for me anyway, is that I do believe that I can take my 220 or my 223 out of the safe and shoot groups somewhere under 3/4 inch. All that would be with handloads. I don't think I'll ever get there with my 260 and that real skinny barrel. I think I can shoot 1 inch or less with my 270, but before I'd ever bet any money on it I'd go shoot it again to check. I've shot great groups with the 260 and the 270, but won't make the shaky claim that I can do it any time and all the time, and certainly not under all conditions.
I sort of think that everyone bragging on groups tends to remember and talk about the best ones. I know that I do. It's pretty easy for a person to convince himself that a great group was due to him, but a less good group that had a flier was due to that one piece of bad brass that he should have tossed.
Back to the OP's question, I used to shoot 5 shot groups, but now with certain rifles I'll shoot 3 shot groups. That skinny barrel 260 gets hot pretty fast. And I'll clean after 12 or 15 shots, just so the next groups get shot with the same degree of bore fouling. After I think I've found the right load, I'll usually shoot 3 rounds the next day, when the barrel is as cold as it'll be when I go to the woods. If they hit where they are supposed to, I've got my new load.