Whether or not someone was a good shot is somewhat out of the question when it comes to battle, with the exception of skirmishing and sharpshooting. Aside from the points mentioned by Leftyhunter, the blackpowder smoke usually made it difficult to see anything beyond 10 or 20 yards after a battle had been underway for a while, and I imagine it would be a bit difficult to take an aimed shot after marching however many miles while loaded down with gear, if that was the case.
I think a better question would be who could march the farthest or who generally had a better record in battle. As M.Warren said, that would best be determined by comparing units.