First shot accuracy is important today as it was back them... BUT what if you were defending yourself back in the day? Being able to reload quickly and efficiently is the sign of a skilled shooter/warrior and was essential for survival. It was also one of the reasons the military and militia used paper cartridges. A humane ethical hunter also finds a use for speedy reloads.
The old dead guys were pretty fast at reloading when they needed to be. Of course, range shooting does not require speed-- actually speed might be dangerous on the crowded shooting line and also ruin accuracy. But speed was a natural acquired skill and important for survival and humane ethical hunting back in the day-- and today as well.
Build your loading skills just like you do your other historic woodscraft.