Every firm dresses this up slightly differently, but the shape is almost always the same five stages. Here's what each one actually involves, using my own OC&C process as the concrete example.
One to two pages. This gets screened by a real person against what the firm is actually looking for: not just keywords, but evidence of grit and standout experience. More on what "standout" means below.
Usually pre-recorded, a handful of questions (mine was 3, via Willo), answered straight to camera with no interviewer on the other end. Treat it like a real interview. It's a genuine filter, not a formality.
A timed, GMAT-style test: quant and verbal reasoning, usually adaptive, so it gets harder as you go. No calculator. Practising mental maths and data-sufficiency style questions beforehand pays off directly here.
Typically two 30-minute interviews, with a Consultant and a Manager. Approachable in tone: basic cases, easy maths, some graph reading. This is testing whether you can hold a structure, not whether you know a niche framework.
Two 45-minute interviews with Partners. Cases tend to sit in broader, less familiar industries, less "learnable," more about using judgement live. Still practicable with the right prep, just a different muscle to the first round.
Uni prestige does get weighted heavily. That's just real, and pretending otherwise doesn't help anyone prep properly. But inside that pool, the degree itself matters far less than people assume.
My cohort of 22 at OC&C was almost entirely target university: Warwick, Oxbridge, UCL, Imperial, LSE. What separated people inside that pool wasn't the degree, it was whether they could talk credibly about a real project and about what's actually happening in the world.
Firms don't all run cases the same way. Knowing which one you're walking into changes how you should behave in the room.
The interviewer drives the structure, feeding you one sub-question at a time rather than letting you run the whole thing yourself.
You build and drive the entire structure yourself. The interviewer mostly stays quiet and lets you steer.