> What do you think about giving the candidate an opportunity to get advance notice of that you'll be asking that question, in an interview, and ask them to prepare three to five bullet points to discuss?

Depends on the level you want to interview for. For a higher-level position, I don't think it's unreasonable to rely on someone's communication and presentation skills to adapt on the fly. Explicitly tell them that they can take a minute to think about it, rather than having to have an instant response.