This was a good video on energy management. While I do like timeblocking I also recognize that it's important to take big breaks. I have often called this the mullet method. In short, I work hard from around 6 - 9 then I take a 3 hour break. In the afternoon I work from 12 - 3 hard and focused. Then I call it a day.
I work very hard to be all business up front and take no meetings until after noon. How you start the day is often predictive of how your day will go.
If you want to read more about the timing of events in life I recommend When by Daniel Pink