For me, I don't use autoresolve too often; it's much more fun to actually use the troops you recruited in battles. The way I see it, however complex the campaign management is, it's only a vehicle to watch your empire crush the enemy in direct confrontation.
But if a full stack is up against a single unit of militia, why even wait for the 3D to load? The battle is over before it even started...
Also, tastes differ: I had a friend who complained that Shogun:TW wasn't playable because he would never win enough battles; turned out he tried to play it like Civilization and always used autoresolve
So, how's your preference?
Do you enjoy playing the campaign part so much that you think battles are a waste of time?
Are you a battle junkie and never skip one, never mind the odds?
Or do you try to balance time and fun, leaving already decided fights to the AI?