Note that this was in 2014 and outside of the US, so our experiences may vary.

As a hiring manager at AWS I conducted similarly many interviews, and can speak to a few things. Firstly, there was plenty of latitude for me to include additional factors in the process, as long as the core elements were present (screening + loop + bar raiser). Recruiters weren't always wonderful at candidate communication, especially when going beyond that baseline. Other HMs certainly included variations and additional steps, so this would not have been without precedent. Finally, this particular team were largely former CTOs and tech CEOs/founders, so there was a relatively high degree of eccentricity and wilfulness present; several of my loop interviews were with these particularly unruly ICs†.

So I could not so confidently rule it a mistake.

——

† Rather memorably, after a solid meeting of minds over the topic of establishing robust SRE practices within public-sector institutions, one such interviewer ran out of the meeting room to fetch me a copy of his favourite book on the topic. This is the only time I received a book for free from Amazon.