on an 06 are the valves more likely to tighten up or loosen up?
Depending on the configuration of the mechanical components it could be
either way.

I have an 06 and am 8000 miles past the adjusting interval and am
wondering how critical this is. If they loosen up then I am in good
shape because I have no noise at all. But, on the other hand if they
tighten up then I probably need to do this

thanks for your help