It's the middle ground that is mind-destroying. Extremely repetitive work lets you turn your brain off or redirect it to more worthwhile thoughts. Non-repetit

It's the middle ground that is mind-destroying. Extremely repetitive work lets you turn your brain off or redirect it to more worthwhile thoughts. Non-repetitive work keeps your brain engaged with the task at hand. The middle ground requires too much engagement to focus on other things but also leaves too many gaps to remain focused on the nominal task.