Microlearning with spaced repetition

You could potentially use certifications.  That could trigger notification to the learner prompting them to retake the course.

Thanks. We’re looking for something a bit more robust. We’re creating learning plans and using the time-based feature. In the Unlock interval section, we enable Set a delay from the completion of the prerequisite courses to the access to the selected course to add a delay (in days, weeks, or months) before learners can access the main course after completing the prerequisites. This option wasn’t previously available, so we’ll test it out and see how it works in the meantime.

Another more manual way to control woulds be to create a manual group of users and tie that to enrolment rules so they would only be assigned once they are added to the group; if that can be helpful.