I've got an 09 yz450 that I bought with 116hrs on it. I'm currently at 131.
According to the maintenance log I got from the previous owner, the bike got a top end, timing chain, valve adjustment at 46.6hrs, and another valve adjustment at 91.2hrs. It doesn't say what the clearances were or what they were adjusted to.
I just checked the clearance the other day, and I was still within spec. 0.21mm on exhaust, 0.11mm on intake. I did not make any adjustments, a new shim would be 0.05mm and would put me slightly out of spec on the high side.
So I'm 40hrs since the last adjustment, and previously he went 45 between adjustments.
I figured I would give it another 5-10hrs, and check again and adjust as needed. Unless there's any reason I should just adjust now?
Also, is it time to start worrying about another top end soon?