In one of my realms, people get gold for how many battles they fight in a campaign, when it is time to refit. It's the same as the old chestnut: you can play as often or as little as you like, but if you want more, you will need to commit more, and with more, comes more responsibility (regarding council and military positions).
That's really good actually; if I ever have a General character with sufficient income I might steal that.
