Losing AI armies tend to fight to the last unit, instead of routing en mass when and the battle ending when the balance of power has shifted hopelessly out of their favor. This results in battles lasting a lot longer than necessary and requires you to do a lot of tedious mop up. Chasing down the returning fragments of units and waiting for reinforcing armies to slowly trickle in is really time consuming and boring with 40 unit armies and large maps, and only results in higher casualties for the AI.
Is it possible for the battles to be decided sooner, like in Rome 2 where the victor is called once the bulk off the enemy force begins to route? If there are some variables that can be tweaked to achieve this, I'd appreciate being pointed in the right direction.