Hope I'm not repeating a thread, but I think people might find this interesting:
https://www.youtube.com/watch?v=2yorHswhzrU

... a guy who (apparently) has re-enacted Hunnic technique to fire accurate shots at better than one every 2 seconds.

Would be interested to hear how knowledgeable people think this applies to real warfare, in the EB and/or Hun migration periods.