I see a pattern where missile units tend to heal the most. Horse archers, archers and skirmishers who only took missile fire themselves, and also melee units who took missile casualties (this is quite noticeable when playing a 'barbarian' faction good many of whom tend to carry javelins).
For example, in a recent campaign (I tend to play awfully sporadically these days) my Cretan archers tended to lose 3-8 men as casualties in every battle, but everyone were healed after the battle was over. This occurred in four consequent battles over several turns.
Troops?
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