C'mon, that's 3 straight days, i.e. skipping 2 nights. How can that be 'the norm' anywhere? Extraordinary claims requires extraordinary evidence - or in this case, just any evidence.
I can reliably say that they’re still very overworked. 12+ hour shifts is the norm, and sometimes even 24 hours.
This vague allusion doesn't do much to convince me of the 72-hour claim. While we're doing anecdotes of extreme sleep deprivation, check out this personal account and AMA of someone who claims to have stayed up for 81 hours straight. What makes me doubt your "multiple people" is that after missing only two full nights of sleep (so ~48 hours), people start hearing and seeing hallucinations, and can't reliably hold conversation, much less deliver healthcare: https://old.reddit.com/r/AMA/comments/6sab7t/i_stayed_awake_...