I disagree. I absolutely love the fact that I can just turn it off after office hours and throw it in a corner during holidays and weekends. Sure, it's a bit cumbersome to take two phones with you, but it's also cumbersome to take the laptop and everything with you all the time. Just put it in the same bag and you're good. Good to note, my employer provides me with a phone, so I didn't need to buy a second one. It also means that if I switch jobs, I just return the phone and still have my personal device.
But if it doesn't work for you, by all means, don't do it. For me the good outweighs the bad.
What you need are good laws, not so much a 4 day work week. I just go to the doctor during office hours and tell my employer I have to go. I even get paid time off for it, like everyone else working in this country. Same for the dentist or any other kind of medical thing.
Sure, it's not always optimal if you work in some sort of shift, but they are required to make sure you can go.
By the way, not that I wouldn't appreciate a 4 day work week, but this seems like a bit of a stretch to say that this is the reason why you would need one.