Something being useful in general does not mean it belongs here. CPR training is a very good thing to provide, if you are qualified to. But I think we can all agree this is not something that we should be doing here.
Good-quality derivations of canonical HS problems is a good thing in general. But this does not automatically mean we should be doing it here.
If the question asks for a derivation, then it will most likely be closed as off-topic. If the question asks for a conceptual explanation of something, then it will most likely be on-topic. Two notes:
- The criterion is the question itself, not its (potential) answers.
- The rule does not change if the question is self-answered, although in practice people seem to be slightly more lenient in applying the rules for these. YMMV.
If you plan to post a question "please solve this free-body diagram for me" and answer it in detail, please don't. It will be closed, and you'd be wasting everybody's time, specially your own.
If you plan to post a question which asks about the physics behind general problems, and then answer it in detail, describing general principles, then by all means go ahead. But again, be careful in how you frame the question/answer. The homework policy does not allow problem-solving questions, so if you don't word it properly it will be closed.
FWIW, my personal opinion is that it will be quite tricky to find a good balance. Low-level physics are for the most part just problem solving. So I'm not sure how you plan to provide conceptual explanations that are neither too vague to be useful nor too advanced for the intended audience. But you do you.