I went in for a technical job interview with a small company where they described the process as speaking with two or three groups of people for about 1+ hour each. They mentioned that they liked everyone in the tech group to meet candidates to get a feel for them. Everyone was friendly and it started great.
The first group asked general background questions as well as some straight forward technical questions and white board programming. Very much the usual, but also some subjective stuff. They then left me alone while they went to another part of their office to find the other interviewers.
At this point the HR contact that originally greeted me came and informed me that the others were quite busy and wouldn't be able to meet. This seemed odd of course. The interview was over and they would be in touch about potential next steps, showing me out. I asked if they'd like to reschedule with the other interviewers, but he said they'd discuss it. As I left I knew there wouldn't be next steps, and a few days later this was confirmed over email.
Obviously not all interviews go well and not all candidates fit. Is it however professional to end an interview abruptly midway if the first part isn't ideal? What if the later parts provided some additional info to offset the first interviewer's judgement?