Why don't you shoot 5 shot groups? Three shots don't really mean anything because your 4th and 5th will eliminate the "luck" factor.
I think it was Col. Cooper who was once asked "What's the smallest group you can shoot?" He then shot the target once. It was a one shot, one hole grouping and you won't get any smaller than that.
I shoot three shot groups. I know alot of guys who do. You're not in a compitition, there are no rules. Most of the guys I know who shoot five shot groups call their flyers. This consists of saying "I'm not sure about that one" or some such thing after the shot. Then if it's good they forget about it. If it's a flyer then they already "Called" it, so it doesn't count against the group size. I've never thought it means much.
There are so many variables when you are shooting that I really don't believe 5 proves any more than 2. What you are truely looking at is the avarage size of the total # of groups you've fired over a period of time. Anyone can get a "One ragged hole" group once and a while. If you do it consistantly over time then you really have something.
JMNSHO,
Scootter