More than 320 Diets were held from 1571 to 1690, but their annual number fluctuated from year to year. The delegates assembled more frequently during the periods of turmoil. For instance, the Diet was convoked more than fifty times between 1594 and 1606, and more than fifty-five times between 1657 and 1667. According to customary law, the princes were required to hold two Diets in each year. The first Diet of the year was convoked around Saint George's Day (24 April). The second or "short Diet" was customarily held around the feast of Saint Michael (29 September), but Gabriel Bethlen persuaded the Estates to cancel it in 1622.