Realistically there are people who shoot faster than even Legolas in the movies does. Supposedely we simply suck and forgot how to shoot the bow properly and the current forms are just very inefficent. Thousand years ago great archers could shoot like 16 arrows into the air before the first one has fallen.
Look at this, it's insane:
https://www.youtube.com/watch?v=2zGnxeSbb3g
the guy never fully draws the bow