I have been playing all day and only 2 of my villagers out of 4 adults are "masters" they have all been working on their individual jobs since the beginning. I have 2 people working as builders 1 is master the other is still adept. I am not sure if this is a bug or not. Both builders had skill to start off with. And my farmer is still adept. I have played all the VV series, and dont remember it taking this long to become a master.