At the exec level, a good 70-80% of your time is probably unable to budge, so 25 hours of discretionary time _is_ a big investment - probably most of your discretionary time for a calendar month. It sounds like it was well worth it though.
And many of these meetings need preparation in advance to be productive. So your time is quickly depleted. Many executives do their deep thinking in the early morning or on the weekends since their day is a day of interruptions.
At least that has been my experience in my last 3 roles.
He was quite senior, so most people wanted to meet him rather than vice versa, so he could 'afford it', which someone in a more junior position probably couldn't pull off.
These meeting were the most effective I've ever experienced. No smalltalk no beating around bushes, there's no time! Regularly I need to discuss 4 to 6 issues with him, which meant my prep needed to be perfect and laser focused. He would read your preparatory docs fortunately, I can't work without unprepared meetings either.
Of course, difficult to communicate ideas (such as in science) require preparation or they are unintelligible and the meetings are a waste of time.
1) the meeting will be as fast as the slowest reader/understander. Personally I dislike having to wait until the meeting to learn about its content in depth. 2) No recall. Many people do not remember things that weren't written down. Good minutes may help, but given the effort investment I prefer good prep docs. More succinct.
Making good materials usually means you can reuse them, so in my experience that pays for itself.
It does nor have to be polished presentation.
That said, the 1-1’s in the article are totally worth the time.