Some are missing the point, most of the work we as software developers does not need long hours but deep focus. The best of the best are able to have 4 hours worth of deep focus, and we are lucky to get an hour or two of it. That would be huge. So the good habits that help us with focus and emphasizes on recovery like walking in the woods (our natural habitat), meditation etc. Its not the time, the hardware of brain…
On the same point, this is one of my primary frustrations as a sysadmin, because sometimes I need to be available lickety-split, but sometimes I need to be in deep focus mode, but my office environment isn't very conducive to deep focus mode... so sometimes I have to disappear myself to a hidden place just to get some thinking in. Or, what happens more often, is that my productivity suffers and I end up staying late…
Jesus! Are you serious? Do they have a good reason or is it literally to keep an eye on everyone to make sure they are working?
If it's the latter, I'd suggest looking for a new job.
Whenever I take a "brain rest" at work, I'm surfing the net and often it's Hacker News. My boss (and her boss) have often walked in, looked at the screen and asked me if I'm reading something interesting.
My company's culture is basically "get your work done, otherwise I don't care how you spend you time".