I would probably say this was an anomaly but too unique not to share. Definitely the longest process I've ever had. If I could summarize the overall process, it would be very disorganized, tedious and disappointing. I had 10 interview interactions (2 were repeated) which encompassed a phone screen, a phone interview and 4 on-site (1 to 4 hour) 1:1 sessions. The entire process spanned across 4 months.
What was originally communicated to me was, the process would be a phone interview with the director and an onsite to meet the team, then a decision. At this point, I'm thinking "Ok, I can make this work" (I currently work full-time and part-time graduate program). However, it ended up being a request to bring me for an on-site with the entire team that week, then it slowly built up through "Oh, the director wants you to meet.. so and so, can you come in this week?" 3 more times. I clarified the timeline at each point of the stage but it ended up being different anyways.
I live about 1-1.5 hours away, so these weren't exactly small commitments I was making on my dime to take time off work, time/cost to travel, risk, etc. I did make it work with a faster turn than I would have liked, to meet the same enthusiasm they were giving me. Met with, probably, everyone that I would have interacted within the team, cross-functionally with an IT/data manager, and with the VP and then a recap with the director after all these rounds. Negotiated a bit on salary. The perception throughout the process seemed promising and fairly positive, only addressing some minor concern about my experience that could be overcome. Fairly intensive process for a junior-mid level position.
Not all was as bad, the interviewers were all pleasant to talk to, very knowledgeable and driven. Plus, it was great to have gotten down that "far" through the process (for my personal experience-wise).
Honestly, if I felt or knew there were issues that I didn't represent myself well enough earlier in the process or came off as an unsuitable candidate, I wouldn't have kept coming back and keep wasting my or the team's time. I don't think it would have taken 4 on-sites and 7-8 people to determine and screen me based on this either.