Good points. Theoretically, you're right, but I don't think it works that way practically. I'm not saying that my time is valueless. I'm just saying that while I value it, there is no efficient way for anyone to compensate me for 6 minutes of my free time. There are too many fixed costs associated with employing someone for that person to get paid the true marginal value of their time.

"No, the marginal income (in dollars) is the smallest amount of dollars that you'd take to work for someone else for those 6 minutes."

Theoretically, yes. But try to find someone who will employ you for just 6 minutes. There's not that much liquidity in the job market (yet?).