> But in order for a 4 day work week to be more productive than a 5 day work week then that means your work output on the 5th day is negative. You are assuming

> But in order for a 4 day work week to be more productive than a 5 day work week then that means your work output on the 5th day is negative. You are assuming equal productivity (per working hour) in both scenarios. However, it just might be that the worker who just came off a 3-day weekend, and knows they only have to work for 4 days before their next break, will be more productive per hour than someone who just came off a 2-day weekend, and who knows they will need to work for five days before their next break. Basically, you are assuming that people are robots and get a certain amount of work done per hour regardless of circumstances.