I like to watch some professional gamer's Twitch streams (particularly before bed, it's relaxing) and I've noticed some have expressed that they can only play 3-4 hours of ranked games a day, while others can play 8-10 with success.
Point is, it seems like I keep hearing about studies which tell me x,y,z etc; but if humans dropped into a zoo on another planet and a study was done to see how long humans could run, I'd bet you'd get some wild answers until you just let the people who like to run go out and run marathons, ultra marathons, etc.
Modern work has some aspect of captivity to it that we certainly subject ourselves to, when in reality we are all individuals with each our own strengths and struggles.