MECE is a useful principle, not a reason to freeze while trying to build a mathematically perfect framework.

Your structure should minimize unnecessary overlap and cover the major drivers of the problem, but relevance and prioritization matter more than forcing every idea into perfectly sealed buckets.

If two areas overlap slightly but lead to different analysis or decisions, that is usually less problematic than missing a critical branch or presenting a generic structure.

Use MECE to improve clarity. Then ask whether the structure actually helps you solve the client's objective. A practical, tailored structure is stronger than a formally perfect one that does not advance the case. For more detail, see the case interview structure guide.

I got much better once I stopped treating MECE like a geometry proof.

My strongest structures weren't perfectly elegant, but they made the next analysis obvious.

I found that second-years who had just gone through the same process gave much better context than generic online advice. In my case, the exact timing around how strict do i have to be about mece in an mba case interview mattered most.