Thanks for your questions - I will focus on answering the first one.
Let’s think on our own why it does not make sense to re-use the same PEI examples across different McKinsey interviews or interview rounds:
- It does not add any value to your profile at McKinsey – repeating the same information to different interviewers is a waste of precious face-time to convince McKinsey about your skills and experience.
- You communicate implicitly that you don’t have a lot of experience in those areas, if there is just one single situation you can talk about in one or more of your interviews.
- Repeating the same example from your 1st interview round in your 2nd round of McKinsey interviews is an equally bad idea. What typically happens in the second round of the interviews is that they will try to better understand those aspects where you could not fully convince the interviewers in the first round. So the interviewers in the second round will bring up this aspect again – and in case that this was a specific PEI dimension, it is not very clever to tell the same example a second time if it was not convincing in the first place.
If I should not use the same McKinsey PEI examples at all – can I use the same situation for different PEI examples at least?
Generally speaking, it’s possible and in any case much better than using the same PEI example in different interviews. However, if you do have the choice, it is better to use different situations also for the different dimensions.
The interviewers will sit down together after the first round and discuss their impressions from each candidate. In case there is any slightest doubt whether or not he should be passed on to the second round, they will also discuss some more detailed aspects about which they are not 100% sure. In case this happens to be the PEI, each interviewer will probably briefly summarize your PEI and give his personal impression.
If now everyone of those 3 interviewers come up with the same or very similar example from you, it just sounds odd and will trigger additional doubts if this is the right candidate, if there was just one single basic situation which was used for all dimensions (questioning whether this candidate has the required experience McKinsey would like to see if there was obviously just one single situation that the candidate could talk about).
I extracted this part from one of my blog posts - you can read the full article here, including an official statement of McKinsey on that topic: https://pei.consulting-case-interviews.com/blog/can-i-use-the-same-pei-example-in-different-interviews/
Hope that helps - if you need tailored advice, please feel free to contact me for a McKinsey PEI coaching session!