There is no McKinsey 2nd round case, same as there is no McKinsey 1st round case. In theory, they are all created based on the same guidelines to assure a certain level of objectivity.
Regarding your questions:
1. Creative second round case
One of my second round cases from a couple of years ago was along the lines of ‘’Our client manufactures and operates check-in machines at airports in the USA. The machines break down at different rates in different locations. What could be the reasons for this?''
This was a typical McKinsey-style creative case, where frameworks will not get you very far. The same types of cases also have to be expected during the first round.
2. Market sizing
McKinsey usually does not do market sizing as it does not fit the format of an interviewer-led case and the evaluation criteria that go with it.
3. My general thoughts on 2nd round interviews
95% of McKinsey partner rounds are just as standardized as the first round, yet be prepared to expect everything. Sometimes they are more conversational and friendly, only with light-touch evaluation, other times they are more challenging. Usually, they are the same.
The reason why you read about freestyle partner experiences is that they deviate from what people expect, hence they post about it more frequently online, hence giving others the impression it is much more common.
Additionally, partner rounds are often perceived as more challenging, just because it's a partner sitting across the table rather than a more junior colleague. It is purely based on the impression and not on the content. :-)
If there are any deviations from the standard interviewer guidelines, expect them to be in the following realm:
- Focus on one or two areas where you were perceived as not as strong in round one, which can be specific case questions or fit questions (or PEI for McKinsey)
- Only doing a case, only doing fit instead of both
- Doing two shorter cases in quick succession
- Challenging your answers more
- Not providing any time for you to think about the answer, making it more conversational
In any case, the most important thing is not to be startled by this and just keep working on the case and fit in a calm manner.
Have a look at the following two articles that I wrote or reach out for McKinsey-specific coaching:
All the best for your second round!