Last March, restaurant sales sharply fell after governors banned in-person dining and consumers began working through their glut of stockpiled groceries. But after several weeks, a new trend took hold, illustrated by long drive-thru lines that wrapped around the perimeter of fast-food locations.

Checkers and Rally's was one of the many fast-food companies that benefited from the shift. With more than 800 locations, it's the largest restaurant chain with double drive-thru lanes in the country.

"We had the most tremendous year last year," said CEO Frances Allen. "We recorded record same-store sales gains and have created significant momentum."

The crisis coincided with the chain revamping its menu, helping revive sales. To keep up with the spike in demand, about two thirds of Checkers and Rally's restaurants shifted one of their drive-thru lanes to handle digital and delivery orders.