Being super-productive isn't always wise for the black belt coder. In the traditional world of commercial programming if you solve the problem in a couple of hours and then just spend the rest of the day fooling around, reading scholarpedia or working on your own pet projects managers often don't look upon this kind of behavior favourably - they think you're not being productive, when in fact the opposite is the case.
From having spent most of my adult life in the world of software development I've noticed that it's the programmers who make a lot of noise, huff and puff, and spend all day battering a keyboard looking stressed that tend to get pay rises and eventually promotions into managerial positions. This is really just down to the limitations of human psychology. If you look like you're working hard you must be being more productive than someone who did the job without fuss, then went out to get a sandwich.