WayOfTheFourElements
Hero
I would, if that was the situation I found myself in as DM.
I'd probably average out their initiatives so a vaguely equal number would fire on each segment (I use 6-segment rounds); unless they were under command in which case they' d more or less all fire at once.
I'd make each roll mostly because I'd want to know how many critted and how many fumbled, and what the consequences of said fumbles were; and partly to get a sense of when the target went down if at all. (relevant if the archers aren't all firing at once, when can they switch to another target?)
In those situations, I always ask the players to help me with the rolls. One person make 100 rolls takes a while; 7 people making 10-15 rolls is much more efficient.