A third theme could be transformation. The closing shift can be a time when the chaos of the day is transformed into an orderly state. The store or workplace goes from being busy and open to clean and locked up. And the workers themselves might transform from being customer - facing during the day to more behind - the - scenes during the closing shift, focusing on maintenance and preparation.
Another theme might be teamwork. If it's a story about a group of people working the closing shift, they need to work together to get all the tasks done like cleaning, locking up, and preparing for the next day. For example, in a retail store, one person might be in charge of counting the cash while others are tidying up the displays. They rely on each other to finish quickly and accurately.
One possible theme could be perseverance. Workers have to keep going even when they're tired at the end of the day during the closing shift.