We had similar backgrounds and he was intelligent and capable, but nobody is thinking strait after an 11+ hour day. And once you start falling behind there is this tendency to either work on meaningless crap to feel productive or add just one more hack for an edge case to close out some, bug you don't really understand.
Nobody's ever complained about the amount of work I get done. The problem I have with this article is that it assumes the more hours you work the more you get done, when it's just not that simple.
Obviously this is personal experience. What I'm trying to say is that everybody's different --- the Treehouse guys are working a 4 day week with $3m a year in revenues. You can't just say 'well, if they worked a 5 day week that'd be an extra 25% more work for them' any more than you can say 'an extra 25% more work will lead to an extra 25% more in revenues for them'.