I've done two long ones - McKinsey Digital (~7 interviews over 3 months) and Bloomberg (~5 interviews over 1 month).

Whilst it was dragging, I do feel they were both adequate processes for me to learn about the companies and the role, and for them to get to know me and my fit for the team. I ended up learning quite a lot about myself, too, and got useful feedback out of the process.

It also was during the pandemic where organisations where finding their feet with remote hiring; I reckon in a pre-pandemic session, they would've been compressed into sessions together.

The scheduling, and comms about it weren't always amazing, but that's down to the recruiters rather than the hiring team, imho.