In a two-player game, we've done about 4 quests so far (To New Roads, Terror on the Prairie, Whispering Leaves, and the Crypt of Kharthuun), and are now in Day 4.
So far the only time we've seen any reference to gaining XP was at the end of the New Roads quest. We filled our Academic Study training in the Progress section of the Dragonholt Village tracking sheet and spent the 1 XP we had from the New Roads quest on a new skill for each of us.
I'm finding it a bit odd that we've only ever seen reference to getting XP at the end of the first quest (New Roads). Are we missing something? Or is XP just super rare?
Depends what you consider to be super rare
Heroism gets you XP when you reach levels 8, 16 and 14 (See last page of Dragonholt Village book).
Considering that XP translate to obtaining new skills, I suspect that you aren't going to get a ton of it because otherwise you'll end up with every possible skill.
There are 24 possible skills, you can start with 8. I expect that gaining 8 more would be around the max. Given what can be gained from Heroism then gaining about 1 per Quest might be all we can expect.