I'm not sure about the specifics of the method as described in the book, but time blocking is a pretty standard technique (if you google "time blocking" you'll get dozens of tutorials on it).
I've been blocking out time on my calendar for a year and a half now. It definitely adds value, as I know what I should be working on in order. Doing it on a digital calendar also means that I can move stuff around or add tasks quickly as plans (invariably) change.
When trying it as my only method of planning, I found that I was losing the bigger picture and losing track of key tasks. For instance, if I put some task to do for Friday but don't do it and forget to reschedule, it's just lost in my calendar. However, it works quite well with an external todo list, as a way to make it more concrete.
It can add or remove stress depending on how you use it. At first I blocked out too many things per day and would get stressed from not finishing them. Now, I block out maybe 2-3 main tasks which I can usually finish and feel good about spending time for myself in the evening.
My partner does this, but she just does it on her Google Calendar. It really works for her. My son uses it too, but he's a student. It's been really helpful for me that he manages his obligations this way because it's easy for me to see what he has planned and offer optimizations to how he's planning his bigger efforts.
I wouldn't be inclined to use it myself, as I have my own method of getting things done. They both moved into time blocking because their previous methods weren't really getting them where they thought they should be.
Both are happier and less stressed working this way.
People search for new systems when their current system doesn't work. I am not shopping for a new system.
I keep notes, wake early, do my thing, and record in Todoist the things I find myself avoiding or procrastinating. Other than that, I have a sense of what I need to do, a desire to do it, and -- maybe most importantly -- a strong sense of what it'll take to get those things done. And a track record that keeps me from ruminating on whether I need a different system.
I've been involved in creative endeavors such that I apply "creative mode" to most of my business and technical endeavors.
Being able to get things done, and feeling satisfied in that effort, usually belies the need for more or different "system".
I have ADHD so time-blocking is fantastic when I can get on a roll with it. I love the pen and paper approach because I can get distracted easily by apps. Daily planning felt too granular for me at first, but I use it to complement my longer term planning.
I usually organize at the week scale, curious about peoples experience planning daily.