2WLK: I tested the quick battle feature a bit. I can't confirm the information about archers at the moment. I tested a battle against 44 lizardmen. Quick battle killed 9, and I killed them all... So, this method needs to be used wisely. There was a case when, with quick battle enabled, I attacked archers and suffered minimal losses. If I have time, I'll look for a save file.
Here's an example from another area. A weak hero with one hydra against a hive of 60 snakes. Test it with and without quick battle and feel the difference. There are many glitches, you just need to apply it wisely, not against every archer.