How about trying this from another angle.
How much gold, treasure and experience would you expect to get in a game.
Per game how many levels would you expect to go up by.
5 turns - Dave managed 3 treasures and I think 2 kills. I managed 2 casts, 1 treasure and no kills in 5 turns.
No fixed length - I managed 10 casts, 2 kills? and 1 treasure and Dave I think 3 treasures Casts? kills?
Not much difference in treasure but leveling greater.
Should we aim for about 1 level per game. Enough gold to buy 1or 2 henchman and a few extras.
Or having seen other games have enough gold to buy your whole warband again and multiple level increase.
With not having tried the other scenarios what game length would suit them.