11 interviews (phone and virtual) was not enough for the team to make a decision on my candidacy.
For nearly 3 months, I was communicating with the recruiter regarding my candidacy for this role. The recruiter would reach out to me saying that "I'm a strong candidate, but they are still interviewing other candidates". I waited for three weeks (after my final interview), but still no decision was made. I ultimately withdrew my candidacy because I received an offer from another company (and they took only 4 weeks from initial call to offer)
My suggestion: If you aren't sure about the candidate, then let them know sooner rather than later. It is unfair to string the candidate along and waste their time.