I agree. Three days is too little (the "weekend" is too long), but four days is just right. I've worked four days for years, now I'm temporarily working five, and I am looking forward to going back. Two days aren't long enough to unwind from the other five, I keep feeling that the week is too long and the weekend too short.

Working four day weeks, every week I'd think "damn, is it the Thursday already?" and on Sunday I'd be looking forward to going to work on Monday

I always feel like I need at least one day to unwind and recover from working hard all week. But then it's Sunday and I need to get ready for the next week already. Would be great to have one day to not be recovering or preparing for the next work week.

It sounds like every week there's a holiday. Weeks with a holiday are awesome.

Yeah, it's exactly like that. Every Friday is a holiday.

But without the holiday traffic.

> As someone who went from working a 5-day week to a 4-day week, I feel like a 4-day week is a 'sweet spot' - I'm just as productive as I was working a 5-day week, but when I work any less than 30 hours a week (e.g. when I take a day off), my productivity always goes down.

Perhaps - but I suspect it depends on the person and the details of both job and workplace.

I spent about 6 years working a 3-day, and it went really well. However, it was more vulnerable to constant-cost outside factors like "unneeded meetings".

> The data is bad

Let me support with an anecdote!