I did go and run another test game.. 4 keeps on 4 different terrain types and recruited 50 revelers on each.. at the end there were 22 with +1 nature and 5 with +1 blood total but the distribution between keeps wasn't definitive enough with such a low sample set.. I just got tired of clicking after that
My first two tests definitely went much worse, this one was at least somewhat close overall. Still not really happy with it though.