Seems like an assumption to say that "time together" is the key difference. For example, at various times in my life when I've been jobless, I did experience similar peeks in my mood over the weekend. But I'm a solitary person and I was not necessarily spending that much more time with others. I would say that the difference was psychological. On the weekend, I felt okay relaxing because I knew everyone else was and the pressure was off of me to be looking for work. During the week, I couldn't escape thoughts about my joblessness. The article touches on this slightly when it characterizes the difference as being more in sync or out of sync with society.