I feel like maybe they didn't do a great job on this, or should have like...at least faked a good result on their calendar...
I'm also somewhat curious when they even eat, some of their schedules require them to lunch before noon (in some case even 11am) or after 4pm, and it doesn't look like they start their day early.
Also what kind of cruel genius plans a daily meeting from 17:30 to 18:00?
Of course with 6 meetings per day you're not going to get much work done no matter how you plan your day, but you can at least try to do it in a way that's vaguely sustainable.
It can also become known that you book focus time, and so people just ignore that you are busy, and book you in. It's also possible that once you are considered fairly respected that people trust you to decide what meetings you will attend.
IMO, Anyone with a calendar like the one in the article should start with a conversation with leaders at the company. This is massively bad for productivity if you doing anything remotely knowledge work related.
Booking focus blocks is a bit of a last resort. The problem isn't the calendar, it's the people and processes in the workplace.