90% restriction for exams in the standard RHLS

I have a standard learning subscription which entitles me to 5 exams and 2 retakes. An exam only becomes available if 90% of the relevant course has been completed. Does anyone know the rationale behind this? It is extremely annoying because there are not many exam slots available in the Netherlands so the first exam possibility is generally 6 weeks or more away. Outside of the learning subscription there is no 90% requirement for booking an exam, heck there is no requirement to have done the course at all! Why this burden within the learning subscription?

Regards,
Rob