Don't forget though that in the days of our predecessors (I think I spelled that wrong), even though you were always on call, you rarely admitted more than 1-2 people in a 24-hour period, and generally the sicker people died bc they didn't have the high tech specialized health care that we have now. After you admitted someone, everyone else would have to get an admission before it came back to you. We also have large groups of patients that didn't used to exist: transplant patients and AIDS patients. Also, at least here in Baltimore, several smaller hospitals have closed in the last few years so the patients that used to go to other places now come to the larger academic centers.
So being on call all the time back in the day meant that you had an admission every now and then, and you had a large number of stable people on the floor (length of stay was much much longer). That being said, if you did have a patient who today would be in the unit, then there was no such thing, so you pretty much moved into their hosp room till they got better or they died.
There was no real need to divide it up into call days and non-call days because there just weren't that many admissions. Once the number of admissions started rising, they started dividing it up into call and non call days. Recently things have gotten worse. My program has been q4 call for at least 10 years. But even in the last 5-6 years, the average number of admissions on a call night has gone from 3 to 6.