I would love for there to be some way to tell the archers to fire or not once the enemy is engaged.
Unless I'm using ulm with shortbow folks, I don't usually want archers firing into a melee situation where they can do more harm than good. I never want volume arrows to go against less than 10 remaining defenders. Again, because it does more harm than good.
What I would really like them to do is advance to the sides and wait until the enemy starts to retreat. Then fire on them as they run from the battlefield.
I presently use the "fire archers" order. But that is less than ideal. Because they will still fire into melee situations. Even when the enemy is more heavily armored than I am. I have lost quite a number of troops to "friendly fire." And usually it's been a situation so clear...where before they fired I thought..."Oh, no...the archers are about to fire!"