I believe I went through five interviewers from various roles as part of the interview process. They were spaced a few days apart, at my request, as I was not in a hurry to get a new job at the time. I was happy that they were willing to accommodate this because I didn't have time in my schedule to accommodate back to back to back interviews in addition to my other duties.
The CodeScience interview process was different than anything I had experienced before. In addition to many technical questions and on the fly solutioning for example scenarios, I was asked lots of interpersonal questions, questions about my hobbies, my family, my travels, etc. This was nice, it made the interviews more like chatting over coffee than being interrogated for correct answers. Even if I had not been offered the job, the journey getting there was enjoyable.
I was pretty nervous for the final presentation to a panel but I got to speak about one of my favorite projects of all time and the interviewers asked me lots of questions about nearly every aspect of the implementation from technical choices I made in the design, managing dev environments, data volume considerations, integrations to other systems, governance processes, version control, testing, automated deployments... it ran the full spectrum. I happily admitted when I didn't know an answer to something that was asked and described how I would go about finding the answer - a practice I would personally expect of any professional.
The interviews went well and I received an offer and started work a couple weeks later, building my first product for the AppExchange.