I'm not sure what "just about as fast" means but let's not get carried away with our enthusiasm for single-shot rifles. Everything else being equal, including the experience, equal amount of practice and ability of the shooter, there's no way that a single-shot rifle can be reloaded nearly as fast as most any repeater, aimed shots or otherwise.
Be that as it may when I was young there was an old man that dove hunted with a single barrel 12 gauge. He kept a shell in the chamber and three between the fingers of his left had and he always killed more doves than anybody.