On the place they worked, hospital, clinic, doctor's office?

Hospitals of course have to have them on duty 24/7, some would run three 8 hour shifts, while others may schedule four 10 hour shifts to allow some over lap or even three 12 hour shifts. The big difference between 1965 and today would be less nurses on duty as hospitals are now after saving as much money as they can.

Also the schedules may vary form one ward/floor to another within the same hospital depending on the head nurse for that department (who would make the schedules for the nurses)