Repeated movements have been implicated in degeneration (wear and tear) as well as building muscle and making people stronger. Which one is it? Do the tasks that you repeatedly perform wear you down or do they build you up?
When a human body performs a task it doesn’t always complete that task in the same way because human movement is imperfect. The brain uses sensory information from the body to control and adapt the motor output to muscles and joints. Sometimes the sensory motor nerve signals go into Chinese Whispers. An extreme of this was achieved experimentally when all participants where given an out of body experience.
Maintaining the variety of movement within your body is different to maintaining a variety of tasks.