That's probably true for typical people. There are exceptions like John Carmack and Jon Blow, who can code for 10-12 hours a day and who are running a mini-crusade on Twitter against generalizations like that. In general, I think you're right though - if you're such exception, it should be fairly obvious to you that you're exceptional in this regard and the rule does not apply to you.
Still they probably have idle time too that really defines those moments of N days at 10-12 hours.
They probably live a way that Bertrand Russel would approve of.
But he was also a terrible manager, as he was thinking/expecting the rest of the world to be as performant as he was.
One of my greatest friends and associates lives for life itself.
When we first collaborated on a project I had gotten a head start on it and was investing crazy hours.
As if it were the rule, I burnt out after the core implementation was done.
That's when his super powers kicked in.
While I had been toiling and feeling like a solo dev for my "heroic" commitment, he had been intimately learning my code and was fresh to build all the required features on top.
I learned a really valuable lesson about the nature of teamwork. To this day, if someone slightly lifts a finger or sounds the quietest of utterances, they're still doing more than I should ever expect.
I strongly doubt that either Carmack or Blow are told by management to work 10-12 hours/day. That they feel like doing it is another matter.