Working consistently longer hours has been shown to be counter productive, in every study I'm aware of. This has also been born out in my role as an engineer and technical team lead managing other engineers and coders numerous times. I doubt Google needs to be informed of this!

You'll note that there's approximately zero 'goofing off' time in his schedule, he's either working productively, or not present at work. This is a good way to be productive and maintain sanity.