There is a significant difference between a framework derived for McKinsey vs. a framework created for other consulting interviews.
At the core, McKinsey wants to see creative ideas communicated in a structured manner, the more exhaustive the better.
Your goal should be to come up with a tailored and creative answer that fits the question. The framework should - broadly speaking - follow these three characteristics:
- Broad: Exhaustive at the top-level
- Deep: Supported with several layers of ideas
- Insightful: Concrete and actionable
As I understand from your feedback, interviewers are interested both in the top-level as well as the lower levels of your answer. While you must have hit some good points (otherwise they would have just rejected you) your framework did not cover the whole issue (not exhaustive) and lacked more concrete ideas and depth to support your top-level (with limited context, be aware!), you lacked some creative ideas, i.e. you would need to go into more detail and qualify your answer with practical examples and more details.
In a McKinsey interview, you can take up to 6-8 minutes to present your structure, your qualification, and hypotheses. This is due to the interviewer-led format that McK employs. The interviewer will only ask 'what else' if you
- haven't gone broad or deep enough
- did not explain your ideas well enough for them to stand out (again, you have time here)
The firm wants to see exhaustive and creative approaches to specific problems, which more often than not do not fit into the classic case interview frameworks that were en vogue 10 years ago...
Again, this only applies if everything you say
- adds value to the problem analysis
- is MECE
- is well qualified
- includes a detailed discussion of your hypotheses
The difference in format and way of answering a question is the reason why I recommend preparing very differently for McK interviews vs. other consultancies.
I think there are three things that you can do to work on that:
- Post the question and your answer to get a more tailored and actionable advice
- Have a look at the article on McKinsey case interviews, which covers the topic more exhaustively: https://www.preplounge.com/en/mckinsey-interview
- Book a session with an experienced McKinsey interviewer who knows what is evaluated and has strategies on how to create exhaustive and deep frameworks on the spot. Obviously the best, yet also the more expensive variation.
All the best!
Keep in mind that they really liked your performance across all interviews, being given a 3rd round is very rate and demonstrates that you are doing a lot of things very well already.