The productivity/time tradeoff is a spectrum, and highly dependent on both the person and the nature of the work. Some people have a sweet spot at 40 hours for certain tasks, some at 60, and a rare few at 80. As a concrete example, think of a software engineer who works 40 hours at their day job but also spends 10-20 hours a week on successful side projects, or a mechanic who works 40 hours at the shop but obsessively tinkers with their own cars in their spare time. Even if the side projects are not directly related towards tasks at their day jobs, they still develop skills that have direct benefits at the day job.

I’m emphatically not saying that expectations will implicitly rise to 80 hour workweeks across the board. For many businesses, there would not be any implicit pressure at all to go beyond the hypothetical legally mandated 35 hours. But for some companies in certain lines of work, there will most certainly be implicit pressure to go above and beyond 35 hours, simply because there are sufficient people passionate enough about their jobs that they will put in more than 35 hours and remain productive.