I recently agreed to go through a 5-round process which totaled to about 6 hours. I'm the first person to bitch about the ineffectiveness of leetcode/hackerrank bullshit for people with 10+ of verifiable experience, but I went through this one because it was a field I had never worked in before, and the personnel I was speaking with were truly interesting.
Sans all of those qualifiers, anything more than 3 rounds is a deal breaker for me. If you don't know if I'm the right fit after 3 hours, verifiable experience, a public body of work, and a list of references, then your company culture isn't a good fit for me.