Recoil is something that usually is only noticed by those who are either looking for it, or are unaccustomed to it. A person who grows up shooting or is in the military, has to conscienely think about it to notice it. Recoil in combat is usually only a noticeable factor if someone is trying to control his weapon for repeat shots, which was not sommething the common CW soldier was trying to do. He didn't care where the muzzle of his gun went after he pulled the trigger.
About the artillery that is very true. A lot of things were done differently in actual practise during battle than was done even in their drill, or in our reenacting. But my point was "In reenacting" you are taught to Look, because your piece may not fire and if you are listen for the BooM you may not know that it hadn't gone off. I doubt that an actual gunner would wait 5 minutes in battle to execute a "Failed primer drill" for example, as we do in reenacting. They would have handled the problem immediately.
And you are also correct in actual battle conditions recoil would be a decidedly greater factor with Artillery than a musket, because the piece would have to be rolled back into battery after each shot