I never used to use time limits in MTW and RTW because as far as I was concerned a lot of battles used to take all day, certainly not 45 minutes max.

But then sometimes on Rome I'd notice something which have become much more prevalant with M2TW- passive ai.

So now I do have them on just because when I'm on the defensive it forces the ai into action.

Although sometimes it winds me up because I've got at fantastic defensive position and the ai just doesn't bother to try and assault me at all.