My real hour game play is 15 hours and i had 2 master builders already. My technique is to keep dragging the villagers i have intended for them to be master class back to building hut whenever i saw the thread of their skill increase same for what i did to my scientist and farmer. This help shortened the amount of time of their walking about doing nothing.
Pressing F5 can change the type of clothings your villagers wearing but take note that you cant change back the clothings once you press that.