The first call was with the recruiter, then a call with manager, a few weeks later another call with a panel, a few weeks after that a presentation and questions and answer session with panel. After spending multiple days and hours interviewing, follow ups, creating a presentation. I never heard a word from them again. Asking candidates to spend this much time interviewing and not following up after is unprofessional. Common courtesy would be to send an email shortly after the final interview to say we did not choose you for these reasons.