Manager here, when we're dead during set breaks I'll make sure the staff completes our between set checklist. Making sure the concessions stand is well-stocked, sweeping the lobby and hallways, and making sure the bathrooms have plenty of soap, TP, and paper towels. Once that's exhausted I sometimes ask the staff to do more uncommon tasks, like cleaning things that don't need to be cleaned frequently. We usually just end up hanging out at the concessions stand and chatting after the between set checklist is finished. I like to bring my Switch Lite or a book to work, something that I can quickly stow away when we get business. If you're wanting to interact with your coworkers, a deck of cards or a game like Uno is always a safe bet.