Not to offend, but I use to rest my hand on the shifter of my old mazda 626 coupe. One day, I was trying to get my mechanic to experience/hear a noise in the rear suspension during a test drive (..I was driving).
He saw me resting my hand on the shifter and asked why was I doing that? I said "doing what", he point at my hand resting on the shifter and told me that would wear out the transmission pieces, including clutch plates, pretty fast.
He summed it up in one sentance something like this...the extra weight on the shifter is causing resistance, the movement of the car and vibrations you feel through the shifter is the transmission fully engaging the drive line - all the pieces work toegether to become one tightly fit piece. If you add extra weight to that, your going to wear it quicker than if you did not resting your hand on the shifter.
I don't know if that's BS :bs: or not, but it seems to make sense. So I broke the habbit.