more shifts for docs = more $$ paying for more medical staff.
I can't speak to the police, but there have been a bunch of studies that showed that handoffs between shifts at hospitals is where things go bad. Someone doesn't document they gave an extra 2 cc of a drug to a patient, and next shift gives them more and causes issues, etc.
Basically longer shifts = more fatigue, and the number of errors caused by fatigue were still lower than hand-off related errors.