Not to say there's anything wrong with putting an extra bit of time in unpaid, but doing it every day means it will become expected.
At my work, we get to take an hour between 12 and 2, people generally know to avoid bugging people in this window and if they do, they'll precede it by asking "are you still on lunch?".
That also depends on how HR defines your time. For instance, we can bank hours as flex time and use them to take personal time (separate from our paid vacation), as needed, as long as it doesn't interfere with delivering what we have scheduled. Good example, at one point the company had a couple of months where we all worked saturdays for a big release. All of that saturday time was banked as flex time and many of us took 4 day weeks for the following month or two. I'm sure my company might be in the minority of valuing employee time like this, but they aren't all like everyone in this thread is making them out to be.
That's only if you don't leave an hour earlier which the author says he does, not in the most clear fashion but the most logical way to read:
> I take that extra hour every day and go for a run with my Golden Retriever (40 minutes) and work on a blog post (20 minutes). I just traded an hour of sitting (like I don't get enough of that) for an hour of exercise and career growth.
EDIT: In the comments (currently the first reply to the first post) he actually says he leaves earlier, didn't spot that earlier.