It's not only not the case that you must do it, it's usually suboptimal, it's just hard to tell that from the inside. He even mentions himself that he's working

It's not only not the case that you must do it, it's usually suboptimal, it's just hard to tell that from the inside. He even mentions himself that he's working at a greatly reduced capacity. If he spent less time at work and more time on himself, he'd probably get more done.