I guess you could say I'm offering a "premium product" either way and be right, but my original point stands. I don't need to be giving 100% to get that money. And the longer I'm at a job, the more I can understand the effort bar I need to meet and influence it downward.
Caring about hours worked is for bad managers, plain and simple. The biggest reason to not work in the office is that it's easier to avoid these bottom-of-the-barrel, butts-in-seats leaders. With them out of the way, you're free to tune your output in such a way that keeps your employer happy while also freeing up your life.
If you're under-loaded, then a good manager can shift the balance around the team. Maybe someone else is over-loaded. If the whole team is under-loaded, then maybe the team can deliver more features. Maybe its a good time to pay down some of last year's technical debt. Maybe its a good time to take a bet on a higher-risk research project.
My peak throughput isn't necessarily there for the company's taking. I guard it as my greatest secret. My manager only gets 2 signals from me regarding load: It's good..or I'm overloaded. Never the truth when I'm underloaded if everyone's happy - that would just be harming myself for some company's benefit.