Lots of people obsessively practice case interviews for years. That's cool, but I wasn't quite that prepared—I had read several books, practiced starting dozens of cases online, and read lots of articles, but had only practiced one live case before my first phone interview. I had put quite a bit of time into crafting a cover letter and resume, and I knew all the common case frameworks.
I think there's a sweet spot of practicing cases where you have a solid understanding of the fundamentals but are still able to creatively combine frameworks.
Each of the 5 cases I encountered in the interview process at Bain included a question about framing, some simple math, and summarizing my recommendations at the end. No one was trying to trick me, it felt like a collaborative process, and a few were kinda fun! (my favorite involved plant-based bacon)
First, the process I used:
Articles from Crafting Cases:
I love this advice from Rohan, a Berkeley grad who chose LinkedIn's S&A program over Bain (boo).
You must have a great answer prepared for "Tell me about yourself" (often the only question I was asked before jumping into cases), "Why consulting?" and "Why (insert company)?" All should have reasons and anecdotes that aren't obvious from your resume.
Hopefully this is helpful... Good luck, I believe in you!