I interviewed for a role in which I had a high skills match. They were enthusiastic through the first three rounds (including in house recruiter screening) and the hiring manager, and then another manager. I was disappointed there was no follow up for several weeks and counting after that interview. (And yes I sent thank yous to each interviewer.) Obviously the organization moved on but I think it's unprofessional or at least not ideal to not communicate for that long, even to let you know they are going in another direction.