As a guy in the physical labor market, the 5 day, 40 hour work week makes sense for most jobs in the industry. It allows you to keep pace with demand if you're in a factory while still allowing for weekends off, you qualify for full time benifits, and even if you arent in a factory, say a welding shop that makes custom cars with a small crew, you aren't looked at as a slacker among your peers. 4 day work weeks may work for some sectors with heavy automation like tech and buisness, not industrial. Things need to be made.