If you check 'late' and adjust, I would recommend getting back on the schedule to keep it simpler. It doesn't say 15K +/- 100%..... If it said 15K and you got to them at 22K I would still check at 30-- all of the gaps are not the same size, and never will be. There will always be a few that are closer to the 'tight' end of the spec.

Personally, checking is relatively easy to do. Once you have the tools, time and technique, clearances can be checked in roughly an hour. Pulling the cams and changing shims will of course take more time than sticking a feeler gauge in the gap between the bucket and the cam.

Shop manual has everything you need as far as what to do when and how.

 

I know its an old thread, but was curious on the interval check and thought this was as good of place as any to ask. Anyone know why the clearance check is 15k in the US and Canada, but 26k in all other countries?

Edit: I found a thread on it. Seems there are different maps programmed with varying rpm's based on what country your in.