Oops you forgot about learning and development: Add two hours (if you care about long term productivity and career prospects). Also standard commute is an hour. So you are left with no free time at all. Not really sustainable.
Unless your office has 20% time or some variation in which case you are only really working 8 hours anyway.
I don't think most people spend 2 hours a day on "learning and development" outside of work (you might consider getting a job where you can learn and develop more, if so). But even if you did, you can take a day off to do that. You're still at 60 hours of work, which is what the blog post references.
I have no idea what most people do. Most of my friends and colleagues spend 2+ hours a day working on side projects and/or learning new technologies.
Unfortunately, in my experience I've found in fast paced environments you learn the minimum to get the job done.
Sure I could switch companies every 18months in order to keep learning via work or i could add a ton of business value at my current company by working a more reasonable number of hours and focusing on my personal development in my own time.
Unless your office has 20% time or some variation in which case you are only really working 8 hours anyway.