No, that's not safe at all. On the context of the article, I would expect writers total production to increase steadily with decreasing hours on that interval.

> It's safe to say 32 hours of work does not produce more than 40 hours.

This is too simple. 32 hours of huge output may produce more than 40 hours of light output. If the machine/human output is a constant, then sure you’re correct. But that’s not true. And that’s my point. It’s relative and fluid. It’s relative to the work, the individual, the health of the individual, the weather that day, and on and on.

But 40 hours includes 32 hours. If you can produce a huge output in 32 hours then you can produce a huge output + 8 hours worth of work in 40 hours.

there would be less time available for rest compared to a 32-hour week, which could potentially lead to reduced productivity

By that logic why wouldn’t the maximum be at 168 hours?

Clearly there is some cost to more hours that causes the maximum to be at strictly less than the maximum. Given that we have no reason to assume 40 hours is better than 32 hours.