On weekday holidays (Yom Tov), food may be cooked, but turning the heat on is prohibited. On these festive days, the domestic needs of the Sabbath observant consumer may require that their oven be heated over as much as 72 hours to allow for cooking during the festival. In the past, one would simply light a stove or oven before the festival began, and its heat was used over the coming days. In recent decades, however, appliance manufacturers have instituted safety features that present a challenge to festival use. One typical challenge is the auto-shut-off which automatically shuts off the heat after a predetermined number of hours.