Some medieval historians have, however, cast doubt on the historicity of the idea. Historian Jenni Lares from the University of Tampere notes that no medieval sources support its existence and argues that it was not a particularly probable dish. Although leftovers were used, surplus food was likely prepared regularly only during festive seasons. For the stew to remain edible, the pot would have had to be boiled constantly, which was not feasible in the Middle Ages. Fires in residential buildings were typically lit only during the day, and they were banned at night in cities due to the risk of fire spreading. Collecting firewood was also time- and labor-intensive, making it unlikely that so much would have been used on a single stew. Furthermore, Catholic doctrine forbade the eating of meat on one or more days weekly, as well as during Lent. On Good Friday, cooking or even lighting a fire was forbidden.[6]