The sad lie of mediocrity
Doing 4% less does not get you 4% less.
Doing 4% less may very well get you 95% less.
That's because almost good enough gets you nowhere. No sales, no votes, no customers. The sad lie of mediocrity is the mistaken belief that partial effort yields partial results. In fact, the results are usually totally out of proportion to the incremental effort.
Big organizations have the most trouble with this, because they don't notice the correlation. It's hidden by their momentum and layers of bureaucracy. So a mediocre phone rep or a mediocre chef may not appear to be doing as much damage as they actually are.
The flip side of this is that when you are at the top, the best in the world, the industry leader, a tiny increase in effort and quality can translate into huge gains. For a while, anyway.
In a highly competitive job market, being qualified isn't enough anymore. Companies are looking for whoever will go above and beyond the requirements, all of the time.