Archers weren’t always on top of a wall. There might have been friendly infantry in front of them, and the archers firing above them into an advancing foe. You’d want someone who can see the range giving the order to ‘loose’ when the range was right, and then you’ll want to make sure they stop shooting so they don’t hit your own side. Can’t have the archers firing at everything that moves all the time.
You can aim your own bow, don’t need a spotter to range for you. I would assume it’s situational, start/stop shooting while individual volley commands may have existed they wouldn’t have been used as often.
Archers weren’t always on top of a wall. There might have been friendly infantry in front of them, and the archers firing above them into an advancing foe. You’d want someone who can see the range giving the order to ‘loose’ when the range was right, and then you’ll want to make sure they stop shooting so they don’t hit your own side. Can’t have the archers firing at everything that moves all the time.
You can aim your own bow, don’t need a spotter to range for you. I would assume it’s situational, start/stop shooting while individual volley commands may have existed they wouldn’t have been used as often.