This type of work schedule is more common in white-collar jobs than in the service industry, but if it's feasible in your restaurant, it does offer perks to both workers and their employers that traditional schedules do not.
The extra day off every two weeks offers a ream of psychological benefits that positively affect employees' professional and personal lives.
However, since the restaurant industry operates with longer hours and larger staff sizes, it does pose logistical complications that make a 9/80 schedule more of a challenge to successfully maintain in a restaurant.