First of all, thank you for your service that you are providing. The emails are for the most part very helpful, as is your website. However, I did just want to make one point. I find topics where new F1Ys give their "tips" on how to succeed a bit absurd.
While I unfortunately haven't been able to crack into the consulting world yet, I was previously in the medical field. I went through many medical school interviews and residency interviews at top tier places and landed top tier positions in a highly competitive subspecialty.
I then sat through the "other side" of interviews as our program made resident selections. Throughout all of these experiences, I NEVER walked out of an interview saying, "here's why they hired me." Of course, one can postulate but to come back with statements as strong as some of the new F1Ys are making seems short sided.
Again, I appreciate all your help with the services you provide. I would just ask you to consider this "little grain of salt" for the future (or better yet, tell me why I'm wrong!).
Thanks for sharing your point of view, I do appreciate the time you took to do so. I am unfamiliar with the resident selection process, so unfortunately we don't share a common reference point. I can say that for consulting interviews, the process is by far the most highly structured (and therefore predictable) interview process in the business world.
The firms are looking for very specific skills that are demonstrated via simulated experience during the interview. Comparatively, there is less emphasis on resume and prior accomplishments in this type of interview.
The nearest analogy I can think of is say someone is interviewing for an emergency medicine residency or fellowship. If we were to "consulting-ize" the interview process, the consulting firm would throw the interview candidate a patient who is bleeding out on the floor, and say, "Go! You got 30 minutes to save him. Tell me what you're going to do, do it, and explain why you're doing it."
If the patient dies, you don't get the job. If you do the wrong things, you don't get the job. If you do the right things, but for the wrong reasons, you don't get the job. If you do the right things, for the right reasons and save the patient, you get the job. If you do the right things for the right reasons, and you run out of time (but you didn't waste any time in the process), you get the job.
Also when you do well in such an interview, a good portion of the time the interviewer will tell you why they said yes, or what was exceptional. This is especially true if the interviewer was impressed by something specific the candidate did (say pulling some super sophisticated surgical technique that you would never expect a new resident to be able to do)... Sometimes as an interviewer, you can't help but say, "wow," in part because it happens so infrequently.
To your point, those who got job offers can't be 100% certain of the reasons. But I do think they can be "directionally" correct.
Also, when you do a case, you can absolutely tell when you're nailing the case. It would be like a resident with a patient with a BP of 60/30 and a pulseOx of 30bpm and 70% oxygenation (you can tell I watch too many medical dramas and spent too much time in ICUs) and suddenly the resident does something and now the BP is 120/80, pulseOx 72bpm, 100% oxygenation... Without an attending physician telling the resident anything, it's unlikely the resident totally screwed up.
The other thing to realize is often these interviewers sit through these very intensive interviews all day long (the interviewers are doing computations alongside the candidates to check their work), and as an interviewer, it is complete torture when the candidate is screwing up royally. Often the mistake is made in the first 5 minutes, you know they can't possibly solve the case now, but you still have to be polite for 30 minutes.
When you get someone good as a candidate, suddenly the interview gets interesting and is fun for the interviewer. The interviewer will perk up realizing they finally got a "live one" -- this is a big "tell" that makes a good 70% of interviewers easy to read. Some have incredible poker faces, but they are the minority.
I guess this is my long winded way of saying, "you're right, but I'd disagree a little with the magnitude by which you are right."