ER docs are. Trained in the entire spectrum of medical and surgical illnesses, and need to quickly assess who is in need of admission/observation and who can be sent home, with or wothout the beginning of treatment. Er docs work "shifts". Can be 8, 12, 24 or during my younger days, 36 hrs on a weekend. The shorter the shift; the fresher the doctor.
Variable. Most er docs i know work about 140-160 hrs a month. Depending on the group/hospital, the shifts are generally between 8-12 hrs. Some do a majority of night shifts, but most have to do some switching between days and nights.
ER Coverage. The hours of most er physicians vary but all work in shifts that range anywhere from 8hr to 12 hr - and most work 130-150hrs per month.