Im confused as to how long it should stay in the oven

The recipe clearly says, "Lay the chicken pieces in the roasting pan, skin side down, and oven-fry until a chestnut brown and crisp on the bottom, about 40 minutes (sometimes it takes as long as an hour). Don’t flip them until this happens. Use a thin spatula to scrape them up off the pan and turn them; cook the other side until the bottom is browned, which will take less time, around 20 minutes."