Most drop-outs happen between enrolment and the first class. A fixed sequence — confirmation, level test, a reminder of the start date — holds exactly the people who had already paid.
Level tests decide the group, and groups decide the timetable. Held with the enrolment, a student lands in the right class first time instead of moving after two weeks and unsettling both groups.
Attendance and fees belong together. Kept apart, nobody notices that a student has been missing for three weeks and will not be paying next month.