Given it's 24/7, there's only 10 employees, and "the store will be in the red if he hired someone for night shifts", 17 hours a day seems plausible for the owne

Given it's 24/7, there's only 10 employees, and "the store will be in the red if he hired someone for night shifts", 17 hours a day seems plausible for the owner/manager (if somewhat unhealthy.)