One of the basic campaign options is to have no time limit on battles. This is great for slowed down kill rates, but does have some awkward side effects....

For example, I had totally wiped out the enemy all bar one unit of harse archers that had not actually got caught up in the melee. I pursued with cavalry...they ran away. If I stopped chasing...they shot at my cavaly. So...I kept up the pressure. They ran..my cavalry followed...they didn't route...but just kept opening the distance to avoid close combat. This went on so long I got bored and surrendered!

I had no units capable of catching the horse archers, and insufficient units to head them off. stalemate. The timer would have saved me! I was defending, so the victory would have been mine...

I have not seen a tutorial around for changing the length of the timer...but if there is one, I would make use of it myseflf!