On my hog I use torque wrenches on anything I can. The reason being is that I have ALWAYS stripped everything I tighten. I just can't tell how tight is tight.
With the small torx on the harley its to easy for me to ruin it and with the drain plugs and O rings its to easy to over tighten it too. So torque wrenches keeps me out of trouble.
On cars we don't have the O rings, just the steel washer/gasket or some nylon you snug it up and good, but even then I know I over tightened it since I don't use torque wrenches on my car for oil changes