It is more likely an interviewer-style variation than a separate experienced-hire case format. Real interviews can be much less tidy than prep materials because the interviewer is testing whether you can keep the problem organized even when they do not organize it for you.

Keep a running mental map of the objective, what you have learned, and what remains unresolved. The ability to communicate clearly while the case moves around is part of communication under pressure.

You do not need to force a formal framework every five minutes. Use mini-structures when a new question appears, state what you are solving, and connect the answer back to the main objective.

Practice a few interviewer-led or intentionally messy cases. The goal is not to predict the format; it is to stay structured when the format stops helping you.

My BCG case was like this too. Felt more like a conversation with random mini-problems.

Experienced hire here. I don't think it is an EH-specific format.

The clean prep-case structure can honestly create false expectations.