I had a rather epic fight with the undead yesterday, they were no real threat but by the end my men were exhausted and a I was scarred some would drop dead or simple be too tired to fight so I understand your point. The problem I suspect is the programming something like you suggest is alot of work one type of enemy. though perhaps the respawn rate could be adjusted to make it a little less of a problem. Not as ellegent a solution from a game play perspective but easier to do from a programming perspective.
