Everyone says go above and beyond, to buck the status quo, but the reality is that the system in place encourages you to fall in line. I could come in as a temp, outwork every person in the building, and maybe I'll get put on as a 4, maybe.
I know the yearly wait time on raises and grade increases is mandatory and you wouldn't want an ultra competitive atmosphere of everyone looking over their shoulder, but someone in the building needs to be looking at productivity and reward it. Maybe have employees who can move up to a grade just below the supervisor, rather than being such a difference between the two. And dangle the carrot of pay increases more quickly as a reward - I know I would work extra fast if I could even have a slight pay increase.
As I can tell, the ones working the hardest are the lowest level employees. Upper management gets to delegate, respond to emails, and sign papers, as well as get full credit for the work of their underlings.