It depends on what you aim, the ratio of ammount of shots in contrast to accuary is already prooved by the trials of Scharnhorst, against a wall - you will hit with a musket in comparison to a rifle the same, in case the rifleman uses a patched ball, against a wall he would use however a cartidge as well, there it doesn't matter it he would reduced the ballistics of the ball, there the wall is so big. So consequently he could shot as fast as a soldier with a musket if needed - especially on a big target, or close one.
So on a big target - it won't matter that much if you fire a rifle or a musket, in case the shooter is trained to hit.
also - the quicker you fire, the higher your puls, the more unsteady your aim, but again, it the target is a wall, this doesn't matter - it you tremble a bit.
This will be in sharp contrast where the distance is long and the target is small, there the rifle will always show its superiority - and the idea behind a rifleman is not to shoot a lot of shots, but only to shoot when he has a target and also if the thinks he can hit it.
A rifleman has a higher probability to hit an enemy skirmisher at longer distance than the enemy armed with a smoothbore musket and using prefabricated cartridge.
I did shoot for a while black powder with a rifle and a musket (with fixed bayonet), there I was a crap shot - it really did not matter up to 100 meter, so the rifle was really wasted on me.
But I did know other shooters who could hit a head sized target with a flintlock rifle up to 300 m - pretty well, they would sneer to shoot at this distance with a cartridge which they did not produce, they would use a patched ball, a powder messurer, a starter, a loading hammer, and a very fine powder for the lock, and they would hit.
As the musket had its use - so did the rifle - seeminly not only the French but also here a lot of readers seem not to comprehend it. It depended on the task - of what you would use, or what the rifleman could use, he was a complete master of his rifle, he could use cartridges on big targets but also patched ball in small and distant targets, it was up to him to decide.
The French army had nothing to counter such a threat - it would be the same if the enemy uses snipers in modern war and you cannot counter that with own snipers.