I saw a teenager who could get off 6 shots a minute consistently with a muzzle loader, that kid was pretty awesome. Three was the bare minimum at the time. An old timer told me the best place to keep a second magazine is in a second gun.

I think they had the same philosophy, they just carried more pistols rather than to try to reload on horseback during a battle. It was a cavalry weapon, you would hold your pistol in your left hand and saber in the right and charge into the enemy. When your pistol was empty your enemy should be within saber range. Then they had the .50 horse pistols because those were intended to shoot the horses of opposing cavalry.