Group Publishing interview questions

Applied. Got an email saying I didn't get the role. Then a few days later I was contacted for an interview; very confusing. First interview with HR was 1 hour over the phone. Second interview was 4 hours and supposed to be in office but over Zoom. HR started the interview, then I did a project. Next I talked to my hiring manager's manager. The very last hour, after I was already hoarse and drained for talking non-stop, I was interviewed by the hiring manager. Why save the most important interview for the end of a marathon? My conversations with HR and the Manager's Manager went well but by the 3rd set of interviews, they were asking the same questions. 100% they should have done a panel to save everyone's time and provide me a better experience.