The 4 to 6 hour day
This reminds me of the thesis of the Overworked American, which was that productivity gains could allow us to have the same standard of living as 1948 and work half as much as we did then. This was written in 1991, and productivity gains have gone up enormously since 1991, so presumably we could enjoy a higher standard of living, or work even less.
Instead, at every opportunity, we've gone for "more stuff" instead of "less work". Pretty stupid if you ask me.