Anchor yourself to the objective and keep creating structure in the conversation. An open-ended partner discussion still benefits from clear hypotheses, priorities, and concise synthesis.

The mistake is either forcing a textbook case format or abandoning structure completely because the interview feels informal.

Answer the question directly, organize your reasoning in two or three points, and be willing to explore a branch conversationally when the partner pushes.

Periodically summarize where the discussion has landed and what you would examine next. That shows control without sounding rigid.

Small point, but I would also watch your pacing. When I rush this type of answer, I usually create a second problem.