Think of a typical evening at a food processing plant. The manager finishes the second shift production and turns the plant over to the sanitation crew—whether an internal team or a contract sanitation company. While the manager heads home to sleep, the sanitation team is responsible for overnight clean-up.
It’s common to think of sanitation as third-shift work that ends the production day. But given that workers ensure the plant is clean and ready to operate, it’s preferable to consider sanitation as the beginning of production, or “shift zero.”