I'm a very enthusiastic worker most of the time, but I have never been rewarded for improving my own productivity at work. Usually improving my own productivity is because of a certain stubborn and personal distaste for intent that can't be backed by action.

I can see why people should improve their productivity at work in the abstract, but I have to admit there isn't much tangible in it for them. They will work 8 hour days however productive they are. Less productive workers are if anything more likely to clock out on time.