How Many Rounds of Interviews is Normal vs. Ideal?

A recent viral comment on LinkedIn addressed how many interviews is too much. The poster, a software engineer, withdrew after 3 lengthy interviews when he learned the prospective employer was planning rounds 4-9 for him. What is typical for hiring in-house lawyers, and what should the right number be?

1. Legal interviewing seems a little longer. In-house lawyers typically go through 5-7 interviews without a ton of complaint. The first interview is a phone screen by either HR (if the person is applying cold) or hiring manager. If that goes well, the candidate proceeds to the second round of interviews with around 4 people consisting of other members of the legal team and at least one business partner. Final round is typically with the GC or other senior legal department manager.
2. I have seen these three rounds drawn out significantly longer whether due to scheduling issues or questions about the candidate’s skill or cultural fit. If it’s the latter, there’s often an internal champion for the candidate facing resistance so more interviews are tacked on to decide.
3. I do not recommend employers draw out interviews. In this hot market, good candidates are interviewing with multiple employers in parallel and rightly judge them by the process. Are candidates being treated with respect? Are processes efficient or redundant? Are interviewers in alignment, or do they have different ideas about the role or say different things about the culture? Candidates often choose the efficient and effective companies.
4. What is the ideal? Four interviews, says Google anyway. An interesting Re:work article about Google reports the company crunched past interview data and found “four interviews was enough to predict a new hire’s performance with 86% confidence at Google. After the fourth interview the accuracy of the mean score increases by less than one percent.”