Yeah, I definitely can't speak to any other province at all; I've been researching Ontario exclusively. But I've spent enough time working in bureaucracies (university admin, no less) to know the left hand never knows what the right hand is doing, so I will absolutely be bringing in my research in case. Always good to know what your rights are going in so that you can't be intimidated by people who don't understand their own policies (living in paperwork-happy and rule-obsessed Germany has been good practice for this).
It's good that you point out a situation like PRs who are returning but haven't met their ROs, as that sounds like it would be a much different case in the eyes of the powers-that-be than the (relatively) straightforward case of a person who is a dependent of a citizen (not a PR) and who has already acquired a valid student permit. (Of course, I'm already dreading getting confirmation of his actual domestic tuition costs in order to apply for said student permit, as there is no way we can prove enough money to pay international tuition! It just never ends....)
Just so you know you don't lose your PR if you don't meet the residency obligations. PR cards do have an expiry dates so that is the way people end up losing their PR status. They can't get back into Canada. A PR card is just a travel document that lets you into Canada. That's why people try to enter via the US border using a visa exempt passport or landing document or a US passport by air or land. The system is getting there but for example there is no way to tell how many days someone has been in Canada when someone arrives at the border. CBSA looks at the entry and exits records quickly and guesstimates or looks for expired PR cards. Shocking how many things aren't linked. OHIP is brutal and doesn't keep track of whether people are meeting the residency requirements. Most people, including Canadians, don't realize that there are residency requirements for using the healthcare system and you can't just fly home if you get sick and need treatment.