I was mainly talking about 3rd year in the post you responded to. As I've said before, if you treat the first two years like a long-houred (65-70 hour) job, you will do fine. So if you put into it what you would put into that job at the law firm or financial institution, you are going to have the same kind of family time as those folks who hold those kinds of jobs. The facebook/myspace/talking in the library really can't be subtracted out - most people can only study effectively in short, 1 hour-ish bursts, and then must take a few minutes to break. So if you are studying all day (as many do in med school), you will be working an hour, then doing SDN/facebook/chatting for 10+ mins, then working another hour etc. and so on. To a bystander who only notices the breaks, it looks like you are goofing off more than you are. But in fact those breaks are what is keeping you sane and productive, and sitting in that seat for an extended period of time. Show me someone with thousands of posts during the first few years of med school and I'll show you someone sitting in the library for an extended period of time. That's just the way it works -- you don't subtract this, any more than you would discount an employee's work day due to a few trips to the water cooler. You NEED to unwind a few minutes every hour to get that next hour.
Third year it goes out the window. You WILL be working very long hours during your sugery, IM, and OB rotations. You will be on the wards overnight. You will have rotations where you show up when it's dark and leave when it's dark. Really no way to deny it.