Unstructured interviews, bad process.
No respect for candidate's time. Spent approx 6 hours in 4 interview, including C-level rounds. - OK
1 week case study - Good.
But then a whole 'test day' with additional 9 hours? - Honestly felt ridiculous to expect a senior candidate to do this.
After the final round was asked if I would do another round - 'just to make sure'. Red Flag - I declined.