I can totally understand your situation and frustration after the experience which you had in your previous interviews. Unfortunately many strong candidates do not prepare accordingly for the PEI, even though it contributes to ~50% of the overall evaluation - and definitely, the McKinsey PEI is an interview format of it's own, and there are many many specifics to consider - it's not just talking 'something' about leadership etc.
A good main structure to follow:
Using the PARADE framework as a basic structure, please find below a typical sequence including timing. It's definitely a good idea to provide an overview of your challenges to the interviewer ("Intermediate structure") before diving deep.
- Headline (~15-30 seconds)
- Bucket 1 (~1-2 minutes):
- “Anticipated consequence”
- Intermediate structure (~30 seconds)
- Bucket 2 (~8-10 minutes)
- “Decision-making rationale”
- Closing (~30 seconds): “End-result”
You can read the full original blog post here: http://mckinsey-pei-blog.consulting-case-interviews.com/mckinsey-pei-length/
Which aspects to focus on for each of the 3 PEI dimensions (as some examples):
Leadership: Takes on leadership roles, seizes opportunities and takes action, helps to build highly effective teams with a shared vision, is sensitive to the thoughts and feelings of other team members, demonstrates mentoring skills
Personal impact: Positively influences others, shows an interest in other people, self-confidence without arrogance, listens, understands and responds well to others
Entrepreneurial drive: Sets high aspirations for oneself, expects and achieves outstanding results, handles obstacles well, shows signs of entrepreneurship and a willingness to take personal risks
Obviously this is just a start into a rather complex and specific interview format and scratching on the surface. I wrote a book specifically on the PEI some time ago to cover all major topics for preparation, and if you need further guidance of course feel free to book a coaching session for discussing and optimizing your individual PEI examples.
Hope that helps to get you started!
PS: The PEI is really specific to McKinsey - however, the main topics behind the 3 PEI dimensions are of course relevant for a general consulting skill-set, so preparing for the PEI will definitely make you think about important skills you can also use and explain with specific examples for other consulting firms.