Went through 4 rounds. Think there was a very final round I didn't make it to. For the final round I did, I had to present to a panel on a complex policy/safety issue with a prompt that was given in advance. While the prep leading up to this was stressful, the experience was not too rigorous and the panelists were really kind. Took awhile (weeks) to get a rejection but I got good feedback and asked to reapply for a more junior position. Good personalized experience through and through.