The most important is: Do my questions come off naturally, so as to not annoy/perturb the interviewer, and so as to make it clear that I am narrowing in on my framework and not just asking questions for the sake of asking them?
For some people this will be 1 question. Others can get away with 4-6 by "tactfully" asking multiple questions at once or in a nice flow. Same cases don't require any questions. Some cases are complicated/vague and need a lot. It depends!
First: What isn't clear?
Here, you just want to ask anything you don't understand. Naturally, we want to run away from what we don't know...consultants run towards it!
- Do you understand the context provided? Do I know how the industry works and how they company would likely be operating?
- Do you understand the problem/opportunity they face? Is it clear what they're trying to do?
Second: Use GOBTM
Write GOBTM at the bottom of your page in case you're stumped in part 1.
G = Geography (Where to they operate, where are they looking to go, etc.)
O = Objective (Can I clarify the exact objective of this case. I.e. increase profits by how much)
B = Business Model (Am I clear on how the company makes money and what they sell?)
T = Timing (Over what time frame does this solution/problem take place?)
M = Market (Who are my customers? What market do I operate in?)
Fundamentally, you are trying to narrow your framework. You are tyring to ask questions that get you closer to the solution
Never ask an open-ended/vague question. Try to lead with a hypothesis. For example, don't say "How does this shoe company work?". Rather say "I imagine the shoemaking process involves reviewing wood/leather, cutting/shaping it, sewing/gluing it together, and then finishing it in some way. Is this about right?"