How and how much should I prepare for case interviews?
You can expect a successful case interview preparation campaign to take you between 1 to 4 months with 11.5 to 25 hours per week of effort. I arrived at these estimates based on my own experience, those of my clients and the breakdown in the diagram in this article. Yes, this is a wide range, and where you should land in this range depends on how much time you have, your skill level coming into this process, and how mindful you are of your weak points in order to best customize your training regimen.
I’d recommend that you put yourself through 2 to 5 simulated mock interviews per week as the interviewee. Any less than 2 would be insufficient practice of the rhythm and communication of the case interview, and infrequent feedback for guiding your solo practice. Over 5 would leave you with insufficient time dedicated to solo deliberate practice.
Jot down a few notes from each mock interview about which areas you need to focus on so you can use those notes to inform your training regimen. For example, did your case practice partner for 2 consecutive interviews tell you that your math seemed to be difficult to follow? Then increase the frequency with which you practice math by yourself. Being self-aware is critical here. Can you listen to the feedback you are receiving and take it to heart?
However, I believe the most important aspect of your preparation is not the time spent, but how self-aware and deliberate you are in your practice. The best way to plan your training regimen is to do so iteratively based on feedback that you receive in simulated mock case interviews. Pay close attention to that feedback and revise your training regimen based on it. The diagram I'm including in this blog post is a suggested starting point that you should modify as needed based on the feedback you're receiving.
I know that when I went through the preparation process the first time around, I focused on the number of mock interviews that I should hit, but that was a mistake. The volume of practice does not matter. If you practice more but you are practicing negative habits, then your practice is hurting you. You need to be deliberate in your practice and mindful of your weaknesses so you can develop an approach to improve them.