Boxerworks.com

If the torque is off, then the usual indication is valve lash being off. One should not go around torquing the head bolts often. If the valve adjustment is only off by .001" then you have no problem at all. I wouldn't bother with touching the head bolts.

There is really a lot of bad advice out there concerning the head torque. Many are "experts" because they have a keyboard, not because they have experience.

+1 for MS.
No, you cannot check torque by just putting the wrench on the bolt and turning...
On the other hand, if you install new head gaskets, you ought to do the procedure MS outlines long before you see a leak.
I do auto heads after 500 miles and for my diesel engines, use new head bolts. (cheeeep, considering what happens if something goes bad with the old ones!)