If we safely assume that your question relates more specifically to case studies delivered in McKinsey’s recruiting exercises, then my response would be that the best approach is ALWAYS to take the time, as you yourself have mentioned, to pause, order your thoughts in a structured fashion, and then communicate the response in a McKinsey-preferred manner to your interviewer.
This should be done EVERY SINGLE TIME you are posed a question as you progress through the case, and you should always state your intention to the interviewer in every instance that you do this.
A rough (and wholly unscientific!) consensus seems to be that an acceptable amount of ‘pause time’ is as follows:
I - Initial question: 60 – 90 seconds
This is only true if the initial question asks you to develop a structure, come up with the pertinent issues to test in the case study, elaborate on a few initial ideas, etcetera, etcetera. This seems to be a common opener question with McKinsey case studies. However, if the initial question is not as described above, then please see below.
II - Case questions as Case progresses: 20 seconds (preferably less)
Focus on being structured, exhaustive, creative, and all with a demonstration of business judgement and insight in all cases. Also follow this standard if your opener question is not a question related to initial problem-structuring.
III - Recommendation/Finale question (if asked): 60 seconds (less if you can)
This question does not always appear. Or, when it does appear, it may not always be worded in such a way as to be obvious that it is a recommendation/finale/wrap-up questions. However, for a final question, this amount of time would seem appropriate.
4 Things to Note:
- The above commentary relates only to McKinsey-style interviews to which my limited knowledge of interviewer-led Cases concerns.
- You should follow this approach even when a question is purely qualitative and straightforward.
- I agree that dynamic conversational flow is impaired by this approach, but McKinsey consultants themselves will (usually) preface the start of the session by warning you that you may be severally interrupted during the interview as they take the Case in different directions. That a comprehensive dynamic conversation for the entirety of the interview will not likely be possible is well-understood and accepted.
- Off-the-fly responses with McKinsey can be penalised. In the event this does happen, it will possibly be cited in your post-interview feedback as an area to address as you progress through successive rounds.
Source for this information:
a few consultant colleagues presently with McKinsey, feedback from a McKinsey coach I have worked with, feedback from trusted Case partners who have interviewed with McKinsey, miscellaneous anecdotes from forums where candidates have discussed their experiences with the McKinsey interview process.
All the best in your upcoming interviews!