[rayiner]

Anecdotal example: I used to work for a small company where the programmers did both algorithmic design and the implementation. Looking back on that work, I could write code to sling bits from point A to point B all day (and did the 12-16 hour weeks you mentioned for months on end). But there is no way in hell I could do algorithm design for 12+ hours a day for weeks on end. It's extremely dense work. There's no mental breaks while waiting for the linker to run, or long stretches of babysitting the program in the debugger, or breaks of mechanically typing out something you've already thought of. It's just you and a pad of paper, thinking the whole time.

The article refers to mathematical work, which is by its nature very dense, much more dense than other intellectually-demanding jobs like programming. As a programmer, you might spend half an hour now and then thinking through all the potential race conditions in a parallel algorithm. But you don't do it non-stop all day, day in and day out. Most of your time is spent on things that require far less concentration.