It's a pet peeve of mine when bankers or consultants complain about 3-4 hours per night of sleep. There are sprints and periods of crunch time in every industry. But having known (and lived with) friends in the hardest working rungs of consulting and banking the only reason they would consistently be limited to 4 hours of sleep is if they were out drinking and blowing coke every other night (and not in a job-related networking sense), and had poor time management skills to boot. The only people I've known who legitimately have no personal free time are surgical residents.
+1. It's definitely not sustained. Several friends of mine at the MBB consulting firms tell me it's like a dysfunctional relationship: They'll give you a killer project, working 80-100 hours for three months. Then just when you've had enough and are about to quit, they'll put you on a lifestyle case in your local city and you get to leave at 5.
The bigger issue with banking is the unpredictability. Even if you have no work scheduled for a weekend, folks are reluctant to leave town or even go on a day trip to rural areas without cell coverage, just in case they get pulled into a deal or client work.
