4 days a week doesn't mean you do 4 days worth of work. It means to me that 5 days worth of work needs to be completed within 4 days.
That's the entire premise behind the book The 4 hour week.
Honestly watching organizations, good management can do a lot to move to more efficient work.
Back in my early career everyone had to take an effective meetings course (it was short), and if people violated the rules, it was expected to be raised as an issue.
So we always had stuff like.
1. Agendas and decisions to be made.
2. Ideally most background data provided in advance etc.
Almost no organizations do that.
The one REALLY easy thing to do in a meeting, is to set the time of the next meeting while everyone is in there.
I was shocked how many groups did meetings without agendas, or without providing background info in advance, or people not reading the background info.
Then the "we'll meet in month", then in a month the scramble to find time.
Those types of problems are a management failure.
The best thing about one place was that the meetings were planned so well, we just had department reps go through and basically checklist the agenda, 80% of the people who did the work for the meeting didn't even have to show up. FYI, the reps weren't necessarily managers.