I always played with the timer in RTW, but never really relied upon it---battles almost always ended pretty quickly and decisively. I think I ran out of time on a siege once when most of my siege equipment got torched and it took forever to get the troops up a single ladder. In M2TW with the passive AI you have to have the timer or else you end up with nothing happening (or being forced into a suicidal charge in order to get it over with).