> It doesn’t understand ‘ooh I need to memorise this course’. It doesn’t have that function. They stare at their keeper and follow orders.

You are drastically underestimating the intelligence of dogs. they absolutely DO learn a course they've been on before, and the smarter ones will pick it up very, very quickly. This is true of other things too, not just agility.

My wife trains sheepdogs (she raises sheepdogs and sheep for a living). The entire point of buying and breeding such smart dogs is that if they're trained right, most of them do come to understand what you're trying to get done, not just their commands. Sure, some people do train their dogs to be "mechanical," just left, right, stop, go, but most aren't training for that, it's an exception. When you have a working dog that has done the same jobs with you every day, day after day, they normally understand what you're trying to get done, which job is next, and with the better ones and simpler to medium difficulty tasks you can just tell them it's time to go get it done and they'll go do what you need them to do (adjusting on the fly as needed, because when you're herding live animals there's no "fixed course" like with agility that they can learn by rote). You're often only giving them instructions when something is going wrong and they need help.

> The dog likely wouldn’t ‘learn’ anything from pre running it anyway.

Shows how little you know. I have started learning with my new dog. We spend an evening on a single course learning moves to control our dog, "front cross", "serpentine", "threadle" etc. By the end of the evening I can still get it wrong or forget where to go next and my dog happily carries on without me and performs the next three jumps correctly (probably wondering why he is partnered with an idiot like me).