Rules changed in 2003, but until then medical residency programs routinely had doctors working 100+ hours a week or longer. In 2003 a cap of 80 hours a week was instituted along with a maximum of 24 hours in any given period, but programs found various loopholes around that cap which still had doctors working close to 100 hours a week. So further restrictions were placed so that over any 4 week period there's a hard cap of 320 hours, no exceptions.
At any rate, for most of the HN crowd who work a fairly routine IT or an office job, 80+ hours sustained for months and months might seem impossible, but join the military, work on a ship, work on a farm, work the oil fields, work in investment banking, work in a film crew which threatened to go on strike in 2021 for having 98 hour work weeks for months on end... and you find that while it's not common, it certainly happens in various fields.
