That is correct.
There is one website out there that many applicants use that promotes the importance of market sizing and has a very strong approach to it. They also market themselves very well.
For some reason, however, the word of mouth about this one market sizing course skews the perception of applicants and they invest way too much time working on market sizing rather than other cases and other aspects of cases.
In McKinsey, market sizing is not part of the assessment since it does not fit the interviewer guidelines and how interviews are conducted. Yes, there is the odd chance that some partner in an interview might ask for a market sizing question but that would be an outlier.
For BCG, Bain market sizing can be part of the assessment but also in a minority of cases.
What does that mean for?
Work on market sizing:
- Find a replicable approach that works
- Practice 5-10 market sizing questions
- Focus 80-90% of your time on non-market sizing cases