The 40 hour work week isn't a productivity related number... It's a cultural construction born from early 20th century union political efforts.
For instance in Denmark, the work week is typically 32 hours and has been this way for decades... Works fine for them... Not sure how well it would work in a culture like America where working as hard as possible is considered a good thing... Regardless of how stupidly obvious it is that this screws up work life balance, individual stress levels and by extension individual health, in the country with the most fucked up health care system in the western world...
> The 40 hour work week ... [is] a cultural construction born from early 20th century union political efforts.
This is unabashed union propaganda.
Which isn't to say that unions weren't involved, but there were plenty of other factors involved. I refer you to work such as The Shortening of the American Work Week: An economic and historical analysis of its context, causes, and consequences (Whaples, 1990) which place the shift in a broader context of "wages, gender, ethnicity, religion, age, urbanization, unionization, and legislation" issues, to say nothing of "industrial structure and technology".
One should treat it like the pronouncement that Al Gore created the internet: definitely give the unions some credit, while taking their self-serving praise with a few grains of salt.
There are particularly many part-time workers in Denmark, and flexibility of labour market is high (including close to zero protection from layoffs), and this has resulted in Danes working fewer hours per worker than other Western nations (1490 hours per year per employee on the average) but on the other hand the labour marker participation rate is very high, so Danes work more hours per capita than any Western nation.
When I interned for the Federal Government in Canada my wages were for 37.5 hours per week (7.5 hours per day, 30 min unpaid lunch was the implied structure).
It's the same 37.5 hours with all office jobs where I live, Finland. Blue-collar jobs are 8 hours per day (1 hour unpaid lunch implied), they then accumulate more holiday days so that the annual working time is roughly the same.
For instance in Denmark, the work week is typically 32 hours and has been this way for decades... Works fine for them... Not sure how well it would work in a culture like America where working as hard as possible is considered a good thing... Regardless of how stupidly obvious it is that this screws up work life balance, individual stress levels and by extension individual health, in the country with the most fucked up health care system in the western world...