Hadn't even paid attention to this until I bought my axys, now I can feel confident in taking apart my exhaust valves, they're just like all my old Cats were! Lol
But seriously, I always used to do it once a season but now with better fueling/oiling on these new machines I don't think they get as bad as some might think they are when they pull them out. I used to scrape an eighth inch of carbon off the bottom of my cat valves & they'd be sticky as honey but cat always used way more oil per tank of fuel. I'd agree with probably just cleaning them closer to the 1000 mile mark