Life Expectancy?

Does anyone have a feel for the life of the backlash nuts, bearings, etc on the Longmill? I know the answer is ‘it depends’ overall, but wondered if anyone had some experience/numbers?

I’m starting to do some larger laser projects that take 5+ hours to run. There is no real load on the unit since it is not milling anything, but multiple direction changes and possibly speed changes (I have it set to constant speed to minimize the wear/tear). I’m concerned with lifespan on the backlash nuts with the constant use.