For both immersion's sake AND the gameplay... no XP for slaughtering shattered soldiers.

[Apocal]

How much time of the battle without fight to the end installed involved chasing fleeing units?

Zero, I hit the "End Battle" button that appears when all the enemy units are panicked state.

 

[Ling*]

Zero, I hit the "End Battle" button that appears when all the enemy units are panicked state.

Fair play. To be fair morale is just one of several factors that I mentioned contribute to shorter battles, and although it may be 11 seconds difference on its own but when compiled with mods that adjust armor and hp values as well as mods that improve combat Ai it sort of scales in combination with these types of mods and the effects are more noticeable.

 

[Dionaea]

There are several factors at play as to why battles last 2 minutes. Low armor values, Stupid commander Ai, and not least of all the Morale system.
I said that the morale system is so broken that it isn't even worth spending development time on, if you want to take that to mean it should be removed in vanilla then whatever draw whatever conclusions you will from that. I'm merely suggesting an alternative to the original thread posters comments regarding the system, fight to the death which is in my opinion a better system for the current game.

Most battles ended when the rout began in history and the rout could begin for the stupidest of reasons, smaller armies could route armies twice their size.

As for the game mechanic with bandits it sounds like you are angry that when you finally find a big group of yummy looters to get some fast easy xp for your troops from, more than half of them rout when things turn bad for them. And since looters can now kill your troops in the simulation and the xp given from the simulation is lower that isn't a viable option. Hence you want the AI to stay and fight so your troops get all the juicy xp.

If you really outmatch the bandits they tend to offer to join you or to surrender in my experience.

As for battles in general there have been plenty times where the morale system saved me and my troops, especially early game when you are on a horse fighting looters and down on health and there are still 4 looters left, with one of them having a pitchfork. And then, whilst cursing at yourself that you forgot to save it for the savescumming and getting ready to start all over again or reload the save from an hour ago, you hit a looter with your sword or your spear and 1 or 2 start fleeing, and one of them is pitchfork guy at which point you realize you suddenly have a chance at survival! And the sun starts to shine in your mind again and all things are good again.