Quick battle.

A couple of times, while replaying one of the campaigns as Irina (Defeat and Victory), I decided to try a quick battle. The AI is terrible at it! It constantly loses 1-2 archers, even though I could easily win this battle without losses using healing and regeneration.

This is normal. Although sometimes, the AI manages to win without losses in a quick battle. I even applaud it sometimes :). But if there are losses, I replay. Towards the end of the campaigns, I relax and ignore losses of +-5 (of course, not elite units :) )
Although sometimes, even if the AI wins without losses, you notice with horror that this scoundrel spends a considerable amount of mana :).