It's a lot of wasted effort and risk, is what I'm saying. You really think that us being locked out to try to repel the assault, they'll take the chances of opening up the gates to slip out some healers?

Furthermore, you really think the guy who just got opened up by a big fuck-off weapon or just had his head or chest stoved in is going to want to jump back into the fight after getting healed? Gotta factor in morale and if and when we break and have to retreat back behind the walls and sit through a siege. Besides, if your wounds are grave enough to need a healer while you're in combat, you've got bigger problems than getting back into the fight. This isn't an RPG where you can chug some healing potions or have your mage buff you or heal you so you can continue to fight. I'd say that's a bit "writing to win" which we wag our fingers at here.