I see... It's a guessing game until you're experienced enough with it.
Sadly, even though I know the feature is there, I often forget to use it in the heat of battle. It must be ingrained in the brain that
infantry units = C key, as real life soldiers are indeed cautious when it comes to staking a life on the battlefield. (to this end, maybe more SP scenarios should
heavily emphasize the importance of preserving life than rushing V-hexes on a very limited number of turns
).