What happens if you don't? Maybe bad stuff. There'* gears and bearings in there, and a coupler
The oil cools and lubes everything in the nosedrive. It might even be low/empty and you might not know.
I do mine every year. Might be overkill, but I do the drain/fill, run for 5 minutes, drain fill, run, drain/fill every year. I wanna baby it, especially with the smaller pulley on there.
Techinfo is for you, bud.