[ppbon]

... get all bent out of shape about tightening torques and trying to be perfect about it.
Most of the torque-wrenches sold on the market don't get calibrated regularly and the values have to be all over the place.
Most of the time a more-or-less tightening is what's done.
I am extremely conscious of torque values in only selected places such as internal engine components, etc. where I use a digital and calibrated torque wrench to follow the specified values. Also in these cases the pattern used in tightening can be as important as the torque applied.
For most jobs I just do a "manual" tightening.
After you've tightened a few fasteners in your life you get a "feel" for it.
It's like golf. You should always have the same swing, the difference in each shot (long game or approach) is the club.
In our case the difference is the wrench. You should tighten basically with the same hand strength, but using a 5 in wrench vs a 12 in wrench will offer vastly different torques on the fastener. That's why each wrench is a bit longer, depending on it's aperture size.
Most people also tend to over-tighten fasteners.
I constantly get cars where the owner has completely sheared off a fastener due to over tightening.
Use a torque wrench, but don't despair if you can't find a particular torque value to apply. Use common sense and your feel for the fastener's size.
Happy Boxstering,
Pedro