I wouldn't worry too much about the 70-80 hour estimates--numbers are a lot fuzzier than you might think! Some examples from my schedule: I spend, on average, some 10-12 hours per week in an unofficial Latin reading group. I'm a medievalist, so I could count those toward my 'work' total (if I did, I'd definitely break 70hrs/wk!), but because I'm crazy, I tend to think of it as relaxation time instead. Likewise, what about the times I decide to 'study' at the coffeeshop where a lot of people in my program hang out? Chances are my productivity will be halved--and my work-time doubled--but for sanity's sake, I do it anyway. Probably, if I did all my work in the library at full speed, no distractions, I could cut my overall time working by a third or more, but as a quality-of-life issue, I won't. Basically, you make your own schedule, and whatever you choose to do will be right at the limit of what you *can* do.