I think Doctor is useless I mean all they do is eat and heal, So they should able to restore little bit of the sick villager's Health at same time as they cure the illness, maybe by 1 point when that doctor is trainee, 2 healths more (3 health restored in total) when that doctor is Adept and at last 5 health when that doctor is master.Yeah the hosptal and herb mastery can effect amount of healths restored.