I prefer 10 rounds groups at 25 yards when evaluating loads for my autopistols. This gives me a repeatable group size. I work them in 0.2 gr. increments. With a new bullet, and various powders, it adds up quickly. Same with a new powder and various bullets. With a new gun, testing various bullets and various powders... well, lots of testings! If one load does better than the other in the rest, chances are that it will also do better than the other in the hand. But, the rest will not get tired after a few groups.