Anything fine motor, even if the motions are changed, will inevitably cause problems. The duration doesn't have to be that long -- I could feel the fatigue in my eyes with eye tracking after just 30-40 minutes. The irony of course is that my eyes are doing fine motor control all the time, but when you do it as part of a control-loop then _something_ (neuromuscular?) will cause you to go into RSI mode and you fatigue quickly. If you don't pause for the fatigue you can do permanent damage -- which is what happened to my hands on the most non-ergonomic Apple Newton keyboard.
I use fine motor control for pleasure, not just work.
I use fine motor control for pleasure, not just work.