But how much power do you really need? When you do a skirmishing charge, the guy with three arrows in the chest may not immediately notice that only a single of them penetrated into the body for two centimeters. You probably would have had a hundred of such archers, all charging by on horses, which is bad enough for morale as it is. If you have arrows bounce of your shield and helmet faster than you can count them and the same is happening to the guys around you, I would expect most organised defences to crumble pretty fast. And when you want to go for a killing shot, you can just adjust your firing from fast and weak to strong and slow at any moment. Knowing the technique doesn't mean you have to use it all the time.