by ben reynolds.
You could use activity completion at the very end of each course to "unlock" an activity with the enrollment key for the next course. Set the next course to require an enrollment key and allow self enrollment.
I have not tried this method.
We use your method here. Because have both session-based and individually-paced courses, we are basically uploading a csv daily, which is probably what you'll need to do monthly if the students are not all in the same course. Course completion will help you with keeping track of who is where.