In most western countries a 7 day workweek without compensation in the next week would be illegal. I wouldn't worry about production, I would worry about the health and sanity of the workers.

Interesting side note, iirc the soviet union actually had a 7-workday-week for a few years. Didn't really work out, I doubt that's any different now.

@imsmn, I think you've misunderstood that source (which I concede is confusingly worded). The Soviets never had 7-days-each-week working for the workers. It was the machines that were worked 7 days a week, by rotating shifts of workers who therefore ceased to have a collective day off (similar in that respect to modern capitalism). They didn't cease to have days off as individuals. What therefore suffered was community life and morale.

What exhausts workers is not the number of days worked but the intensity of the work (for which hours of attendance are a rough proxy). I could easily do one hour's work on 7 days a week. It's like eating - you can eat big meals periodically, or you can eat small snacks constantly. What you can't do is eat big meals constantly, and eating small snacks constantly would have a fixed overhead (such as having to stay near the kitchen cupboard), so the most efficient and flexible disposal of time is to do different activities in bursts.

When weekendwork is needed, there are usually 10-14h workdays (breaks not included) and it's work on the computer.

I don't want to go into the discussion if it's legal or not, I'm more interessted in the productivity gains/losses

This question needs more clarification. There are major differences in productivity between doing simple manual work and doing creative design work. Defining productivity and how to measure it is a constant problem in design work.

@JoeStrazzere It says here that 2 months of 60hour weeks have less output than 2 months of 40 hour weeks

@JoeStrazzere When I was a young and foolish software developer I worked thru the weekend a few times. Not that the company was a sweatshop, I was really interested and engaged in the work. It was a serious mistake. In those cases I spent all of the following week in a bit of fog, a bit confused about what day it was, feeling like every day "ought" to be Friday. I'm sure I was way less productive. So I wouldn't be shocked if going 7 days a week for 2 months resulted in less output that working normal hours.

@DaveG - I understand that not everyone has the same capabilities.

Are you asking because you can change things or are you asking because you don't like the way things are but don't have the power to change them? If you can't change things, get out of that company.

@JoeStrazzere It's not a question of capabilities.

@DavidR I don't have the final say, but I would like to change things. But if it's proven that OT and WE work helps there's little I can do

But if I have proof that... is better, I might get a shot in trying things

@DaveG - we'll have to agree to disagree. Some of us have worked many days in a row without fog or confusion. And some of us averaged far more than 40 hours per week over the course of their careers.

@JoeStrazzere I agree that we disagree, based on not just my own experience but by observing many other people who had the misfortune to work on "death marches". It's like multi-tasking: people may think that they can multi-task. They can't.

@Frezzley Because of the range of capabilities in the human race and because of the many different definitions of "productivity", it is impossible to "prove" one way or the other. Instead, what you need are the stories from companies that have mandated no overtime and no weekend work and are a lot more "productive". In a fast-paced environment, the companies that are flexible and able to learn are the ones that survive better. In most cases, that requires more time off to accomplish. In a slowly changing environment, overwork pays off.