Well, I for one have never finished a game, technically. But then I love the World Map (339 provinces), like to play against 17 impossible AIs, and thus am usually doing something else while the AIs are playing : it takes several minutes per turn ! I figure I put in about 3 hours on week days (remember I can do something else at the same time
) and a lot more on week ends...
In my current (Mictlan) AAR, I'd say I play 5 turns/hour, on average (with the time needed to take notes, occasional screenshot, and the occasional backup of the game folder so I can come back for more screens if I ever want to)