Originally Posted by
Andrew R Stewart
This just reinforced my belief that the bolt/nut should be slightly loosened before retightening when checking for torque spec.
This.
If you're using a beam-type torque wrench, you can see how much a bolt is over-torqued; if you're using a click-type torque wrench, the only way to know that a bolt is at the correct torque (vs over-torqued) is to back off a bit and then tighten it.
Of course, if a bolt is visibly loose, then just have at it.