What do investment banking interns (and bankers) do which benefits from such long hours? Lots of manual data processing? Reading? I absolutely benefit from uninterrupted stretches of 12-24h working on problems sometimes, but only infrequently -- usually hit diminishing returns between 4-12h. The only times where I've been useful >24h was when the task was more "set up this thing which has lots of waiting on other people or long-running processes", or in some cases where external factors (transportation costs, outage window) meant a single 48-72h sprint was worth more than maximum productivity during that period -- and even then, some level of rest during some stage made a huge difference.<p>An entire summer of 17h days is difficult to imagine as a productive way to work.<p>"It's just hazing" is a reasonable answer, but surely that would create a market opportunity for some alternative entity, or at least would mean the hazing has to be limited in duration.