Many of us only work 5 days a week officially, there's many of us that deliberately and knowingly slack off one day a week. Others will just slow down a little to fill the five days. Yet others will use WFH as an opportunity to do a 4 day work week.
> there's many of us that deliberately and knowingly slack off one day a week
Many? I doubt it. Maybe many very privileged tech/big-corp workers in developed rich western countries, but globally that's not that many.
Your argument is exactly the argument companies use to justify not going 4 days a week. If workers already have it so good that they have free time to slack off one day out of 5 days per week what's to say they also won't slack off for a day at 4 days per week once that becomes the norm?
Don't get me wrong I'd be al for it, but your comment proves many already have it so much better even at 5 days/week.
You have a choice. Work at 100%, 60% of the time, or work at 60% 100% of the time. It's not slacking off, it's managing mental health and endurance. You're not at 100% all the time. You're lying to yourself if you think you are. You may be spinning the tires, but the car isn't going as fast as you think it is.
I don't think anyone can truly deep focus 8 hours a day without burning out at some point.