I’m not suggesting external credentialling - schools can perform their own assessments. I’m just suggesting a bridging course. TBH, in this digital era, I would have thought a motivated student could cover most of the content on their own, but the number of times this presents as an issue (the gap between 5.2 and 5.3), a bridging course seems an obvious solution.
I’m far from a fan of coaching colleges, but many who frequent this forum attend them, so I think a bridging course which enables students to bridge a relatively small gap so that they can study a desired subject at school seems more worthwhile than the many other services I’ve heard of them offering.
I agree with your last suggestion and that’s saying something as a parent of a student who was in a MEx2 class of three students which, wrt pace, catered to the student who couldn’t score more than single digit marks as percentages in tests, because he thought he would need the subject to be an engineer. He was the group’s rate limiting step for two terms (when he finally dropped out) and my eldest ended up having to race through a third of the course the month before the HSC exam. I think teachers do need to pace their teaching to ensure all topics are covered in a timely manner, but within reason, classes ought to be as inclusive as possible, the elephant in the room being school rankings based on HSC performance.