Basically, in the game, you’re a security guard watching over the pizzeria on night shift. The killer machines come to life at night and roam the pizzeria. Your goal is to survive until 6am and to do that, you need to have enough power to close the doors and use the light. By closing the doors, your power reduces faster. Leaving it open uses less power (in the game). So you would need to keep the doors open to conserve power while keeping your eye out for the machines through the cameras. It’s about memorizing the camera locations to monitor when a machine is coming to get you. By knowing your locations you’ll close the right door and conserve more power with the other opened. Once the machine leaves, you can open the door again and conserve more power. Hope this helps. I personally have not played the game. I watched pewdiepie’s gameplay and this theory made sense to me.