[Fot] Head torquing

[EDWARD BARNARD]

Lister's:
I have a question to pose to the list concerning re-torquing head bolts/studs.
Please post your answers on the list for the other members to absorb.
We continue to have blown and leaking head gaskets on Bill Collin's 1300
Spitty. I don't want to muddy the water on the head gasket media to use...just
the "proper" way to re-torque a head.
"We" know that it takes more torque to initially turn a bolt or nut. Once it
is turning the required torque to turn it drops. This phenomenon probably has
a name which has escaped me in the thirty years since college. 
In light of this, when re-torquing a head should you just set the torque
wrench to the desired torque and have at it, or should you loosen the
bolts/nuts and re-torque to spec?
I have wondered this every time I re-torque a head, and the torque wrench
"clicks" as soon as I start to turn the nut. Is the torque correct? Am I under
torque? 
Triumph even had 4 or 5 technical bulletins to address blown head gaskets on
the TR7; one of which stated you should loosen the bolts and re-torque to
spec.
I look forward to the answer we receive from the list of knowledge.
Thanks in advance.
-Ed-