Or sit on the boards of multiple large public corporations.

I've never sat on the board of a company. But I'd imagine its a lot less demanding than a full time job.

It is usually a part time job. You would be expected to take other jobs.

But it's not uncommon to sit on multiple boards at the same time that a person is the CEO in their full time job. It can all start to add up a bit. Are they working extra hours? Does the CEO position not require a full 40 of their time? I suspect there are many in both categories.

If you're talking about Elon Musk, its not really the same thing since he owns the companies he's CEO of.

Musk does not own tesla

He also owns less than half of SpaceX. But SpaceX's management is probably just fine with him going off and focusing on Twitter, they can do fine without him playing an active role.

They probably do better when he's not around.

Which reminds me, I've been meaning to keep tabs on his former head of engineering at SpaceX. That guy is probably the one you should be watching, not Musk.

My mistake. He does hold enormous influence though, I would think.

The difference is that it is usually fully transparent what the CEO is committed to.

CEOs have a fiduciary responsibility to the owners whereas rank and file employees don't.