Really interesting data here on how I can work in more effective "bursts" in order to be more productive. I think it is interesting that the chunks recommended here are in a 3:1 ratio. Also it is interesting that the research shows people cannot do much more than 4-4.5 hours in a day of truly creative work.
I am attempting to design my days so I use the first 90 minutes toward my "one thing" - the most important work I do all day. Then I take a 30 minute break to refocus (sometimes eat breakfast or drive to work) and then do another chunk of time before lunch. The time 1-3 p.m. is pretty "dead" for me so I think my third 90 minute chunk would be 3-4:30 before I get ready to leave for the day. The other parts of the day can be used for minor tasks like email or filing or things that require less brain power. These are my intentions. I may also experiment with a 75/25 ratio or 60/20 ratio at first in case 90 minutes seems like too much time to start with more "deep work".