I'm at 78,000 miles and still using the original rotors. I've used 2 or 3 sets of sintered and one set of semi sintered after the stock set were worn out. At least one of those sintered brake pads sets still had plenty of life when they got changed out.
Miles aren't a great measurement. Where you ride, when you ride and how you ride will make a huge difference, the only way to tell for sure is to measure the thickness of the rotor, the manual has a minimum thickness that's safe to use
Edit the semi sintered didn't last long and one of the sets of sintered got covered in the oil from my forks when my forks had a leak.
2 sets of sintered and OEM set I wore down, the rest got changed with plenty of miles left