I was reading an article about groups, and how much they grow as shots are added. It didn't have anything to do with sights, or ammo, or shooter fatigue, but more like statistical probability. It was pretty interesting, and the basic premise was "three-shot groups are worthless". A ten-shot group WILL be almost half-again as large as a three-shot group from the same gun, so while you may be able to get a three-shot cloverleaf, those three shots would essentially be random shots within a group that included seven additional shots, so you can't draw any conclusions about accuracy, or sight-in, from a three-shot group. When shooting a pistol for groups, I shoot ten rounds, and borrowing from a theory espoused by Massad Ayoob, I consider the ten-round group to be what I can do, and the best six to be what the gun can do. I find that the best six are usually about half the size of the total group.