I use auto_win if a CTD means I need to refight the same battle. Or if I get some random rebels pop up in my lands that i would own with a proper army. And lastly if I am assaulting a settlement with odds of 4-1 or more in my favour I auto_win. Ive found the AI can be funny about that sometimes - especially if there is a FM in the settlement. I have also occassionally used the move character cheat for agents and single characters stuck on islands etc. But never armies.