Your resources have been very helpful for me so far. I am an experienced candidate, and just had my phone case coaching session with McKinsey.
One thing I was a little surprised by was that the case coach wanted me to offer up an opinion straight away as opposed to laying out a structure and asking for information.
For example, I was asked if I felt that another company would be a competitive threat to the client.
I tried to lay out some of the key factors I would analyze, however the feedback I got was that I should consider saying "yes" or "no" right away, then talk through the factors.
Is this typical for McKinsey first round ? It felt a little odd to me to express an inkling or opinion without any data or further information.
In this case, the interviewer / case coach was asking you for your hypothesis up front. This is very common in McKinsey Round 1, where the case interview process is broken down into four or five small pieces, rather than given as a continuous case.
In a candidate-led case common in McKinsey Round 2+, and all rounds for most other firms, you have 40 minutes to solve the whole case. In McKinsey Round 1, you have eight minutes to solve a specific 1/5 of the case.
In the example cited above, you basically had a few minutes to provide your hypothesis and structure the problem in terms of what data you would need to test your hypothesis.