Leaving the map can be a viable strategy during a campaign if things get too intense to preserve your force for the next battle, unlike when you are fighting a regular scenario where you don't have to worry about the lives of your digital soldiers.
Our fearless A0 unit about to issue YET ANOTHER "stand or die" order, because it's turn 30 out of 35 and you gotta do SOMETHING.
Then walks away towards the map edge grumbling to himself, "Order this, spot that. Move here, move there, I'll make em ALL pay."