I would say I average 3-4 hours of listening a day.
I try to listen closely all the time, but the reality is that close listening only happens with about half of my listening. I imagine I'd burn out if I listened closely all the time.
Reading Jeff's post, I realized that I'm lucky to be able to listen to music played through speakers almost exclusively. If I had to use headphones I would, but I wouldn't enjoy listening nearly as much.