This is great and I do it down to 15 minute increments. But inevitably, several times a day: "Can you jump on a quick call?" And sometimes that call is an hour

This is great and I do it down to 15 minute increments. But inevitably, several times a day: "Can you jump on a quick call?" And sometimes that call is an hour and then my blocking attempt is completely hosed and needs to be dynamically adjusted to accommodate "schedule bombs" like those. I also recommend padding meetings/work wherever possible. Back-to-back activity increases chance of being late to next thing of there is overrun (out of your control sometimes), and that can add up like a rubber band effect in traffic throughout the day. Then you end up managing disappointment rather than meeting expectations. Also, learning to say "No" is effective, useful, and empowering. Don't let outside influences steal your time without good reason.