How common is 1 round of interview in cybersecurity?

I’m not sure if this is an anomaly. So I applied for a 6 figure cybersecurity job in a large well known org in the US, and after only 1 round of interview, in-person, I got a call from the HR Talent Acquisition rep about two hours later that I got the job on the same day. There were about 10 employees in the interview room, including the HR rep. There were a few candidates interviewing that day, and the session was about 1 hour. Here are my questions:

1) How common is it that there’s only 1 round of interview in the cybersecurity world ? There was also the initial HR phone screening, but I don’t count that as a “round of interview” since they were just discussing the position and to see if the salary and everything met my expectation before scheduling it.

2) Is it common for an HR rep to be in the interview room the entire time for in-person interviews?

3) How many rounds was your interview, or how many rounds is it typical for your company if you participate in the hiring process?

EDIT1: Obviously, I am not complaining at all. It saves a lot of time. But in about 20 interviews in my entire life for professional roles, I’ve never had just one round of interview, and never had HR sit in on the entire interview.