The printing press fundamentally changed everything so our sources get much more socially inclusive starting with the arquebus onwards (but not so much the hand cannon, which predates the press). This cuts across all subfields of history because society no longer depended on expensive scribes to preserve sources and publish new material.
More importantly, volleys were crucial to breech loading gun tactics because unlike an archer a gunner is very vulnerable while reloading, since they have to hold the gun, load the powder and ball, and pack it down with both hands. The musketeers were in a formation several lines deep so that when the front line fired, they’d go to the back to reload and it worked much better if it was organized. This cadence also informed the pikemen defending them when it was safe to move and reposition. Archers could “reload” from a quiver much faster so there was no point in coordinating it.