Funny this topic should come up. I've rarely needed a quick reload or a second shot. Probably once or twice. But I always reload when tracking a deer I shot at just in case it isn't expired when I come upon it.
One time I jumped a deer and tracked it with the iron sights hoping it would stop but it never did. So I circled the thicket and jumped her again, took aim with my flinter and KABOOM. A clean miss but at the shot she stopped and stood there watching me get out a "speed loader" pour the charge down the bore, seat the bullet, and prime the pan. As soon as I closed the frizzen she had enough and I watched her run away again. But at least my rifle was loaded. Never did get that deer.