I would agree, assuming the patient workload is appropriate, I think it all depends on how busy the place is. I've chosen to do 24 hour ER shifts instead of 2 12-hour shifts in a place that would see about 1-1.25 patients per hour, mostly during the day so I would usually get 2-6 hours sleep overnight. But in a busier place, I would much rather work a 12, 10 or 8 hour shift as the intensity increases, say to 2-3 patients per hour. And the case mix also matters a lot, if you have a bunch of patients with coughs and colds, or minor injuries, you can see 4 an hour easily, if everyone is a demented nursing home patient or requires a translator, seeing 2 / hour might be crazy hard.