I don't know if this is definite so someone may want to verify this, but it seems that if someone is fixing a hut and gaining skill slowly on thier own that if I pick up the person and place them back down on the hut that I get the "this villager has improved at construction" more often. Would lifting them up over and over make the skill level go up faster. I am pretty sure this is what happens with the breeders too. Let me know if I am wrong about this! Thanks!