I am a career Industrial Maintenence Tech so I just use my calibrated elbow on my right arm for non-critical stuff but I use a Tourqe Wrench on the important bits. Very important to maintain your tourque wrench's as well and keep them on "0" when not in use.
i torq head bolts and chrank/rod bolts on car engines but thats it.. i had the head tech call me out on it once, i told him to check it with his torq wrench if he didnt belive i had a calibrated arm, i was dead on on every bolt... but i have been wrenching since i could walk..