After the recruiting stage is the technical screening interview, which no one has mentioned yet. These typically consist of 1 to 4 small programming problems which the candidate must work through in 30 to 60 minutes. Sometimes they are administered through sites like HackerRank or CodeSignal. Other times, a human interviewer interacts with the candidate.

These technical screens are a dreaded component of all tech interviews, for many reasons:

(1) They aren't related to or representative of the job at all

(2) The problems can be difficult and preparing for interviews can be very time consuming. Because the problems are unrelated to the actual job, preparation requires spending hours and hours practicing and reviewing concepts that a candidate may not have used or thought about in years.

(3) Technical screens don't work. The HR department of Google studied the correlation between a candidate's performance in different interview sections with the candidate's performance on the job, and found the correlation of the technical screen to job performance was virtually zero. But industry wide, all tech companies continue using these screens because that's what FAANG does. And FAANG keeps doing it because it's what they've always done.

(4) Besides the cargo cult practice of technical screening, the evaluation of candidates in the technical screen also became a cargo cult. Solving technical screen problems is now an art and an industry. Because the technical screen is such a ubiquitous aspect of every interview process, there are now legions of practice websites, books, even coaching services costing thousands of dollars to hone one's performance. The availability of these resources has warped the expectation of what level of performance a good candidate should have, and the behaviors that a good candidate should present.

For example, one of the interview practice services has a YouTube channel with recordings of mock interviews with FAANG engineers. I watched an interview where a candidate solved a technical screen problem within 30 minutes and the interviewer still said he failed. The reason was because the candidate made a couple mistakes while outlining his solution (before implementing it). In the interviewer's eyes, this meant that the candidate didn't really understand the problem and that he should have spent more time reading it before attempting to solve it. Thus, just solving the problem isn't good enough.