It is impressive and he is very good, I wonder if the bow poundage is adequate for "war". As to quivers, how else do you carry arrows except in a quiver or arrow bag on a march? Speed shooting uses up ammunition quickly so re-supply would be essential, transported in bundles, bags or qivers. Ancient images do show quivers mounted on chariots, for example. Do soldiers fire full auto all the time? I think not.
We could shoot twelve aimed, distance, shots a minute from longbows. Far less than he does at short range of course but it was a given that arrows needed to be deployed en masse to have real effect on battlefields long ago.