Ah feel the serenity.
I love the idea of the 4-day work week, I would need to better manage my time. Since I work from home full time I need to ensure I stick to a schedule as I do tend to work more than the regular hours since I'm so much more readily available.
The 4-day week I think would force you to be more productive. When Wednesday comes around you realise oh no! Only 1 more day left, better buckle down and do the work.
Time management is a real skill and honestly probably should be something that is taught not only in high school, but I think workplaces could benefit from a training seminar or something along those lines where employees who think they struggle with time management can try and improve themselves.
Though for your issue, turning off the computer or turning on do-not-disturb hours for your work IM client would probably be a benefit
I run two entirely separate phones, one for work and one for real life. I tell my partner that my second phone is for my secret girlfriend, just to sound interesting and dangerous but it's really for Teams and email