Modular schools:
Standards Document 39 refers to Student/Instructor Ratios for PPL courses in non JAA states and we use the same guide back here in blighty, as we offer CPL training which falls under Doc 35.
We normally give the new FIs 2 PPLs to start with that's two flights per day per student with time for ground then move up to 3. We have full time students so that seems to keep everyone happy and running smoothly.
2.4.2
A student shall be included in the ratio calculation from the time at which his course commences until the course is completed. For PPL courses the ratio shall not exceed 6:1. Where students attend on a part time basis the ratio shall not exceed 6:1 on any given day.
We keep our Commercial/Instrument courses at 3 per instructor, therefore flying every student flying every day, but about 80% of time 2 per instructor therefore flying everyone twice a day.
Standards Document 35 goes on to say : (CPL/IR courses)
The training program should be arranged such that a flight instructor is not normally programmed to fly with more than 3 students per day.