I interviewed with a company out of SV that did this. They started with 3, added another 3, one hour interviews and finally another 3. 9 interviews over the course of almost a month.

I was being interviewed for a principal engineer. I was very clear and kept saying I wanted a management track position. They kept saying we love your background we can work with you on this. Ninth interview was with the CTO. He said the same. Them ghosted. Wouldn't answer my emails or calls. 9 hours, plus prep time wasted.

The company I ended up getting hired by also did a large number of interviews, 8. And they took even longer. Just over three months from initial contact. They're fantastic to work for, but I do think there comes a point where if you keep digging you're going to find something you don't like.