Use a light structure to organize ideas, not to cap them. Two or three idea families are enough if each family produces distinct options.

A brainstorm is judged on breadth, relevance, and practical judgment. Overly rigid buckets can create repeated ideas with different labels.

For example, separate demand-side, product, and execution ideas, then push for two or three non-overlapping ideas inside each.

After generating, prioritize the most promising ideas and explain why. That turns a list into a business answer. For a related reference, see Case Interview Creativity: Good Ideas vs Bad Ideas (How Interviewers Judge Them).

This came up in one of my mocks and the feedback was basically to stay calm and make the next step explicit.

I have seen people get stuck here because they treat every detail as equally important. Prioritizing one thing first made my answers much stronger.