Slack interview questions

I got to the 3rd round for this role which was the panel interview. The recruiting team was helpful and responsive throughout the process but I found the process of the panel interview disingenuous. Preparing a panel presentation when you are working full time is a big task and I feel Slack needs to appreciate this more. One of the panelists had to leave halfway through my presentation and there was not much interaction/questions from the other panelists. I recommend candidates ask a LOT of questions of the recruiter before they commit to preparing a panel presentation to make sure you're not wasting your time. I felt I was pushed through to this round and asked to do a lot of work when I was not really being considered as a top candidate. Perhaps the recruiters have quotas in terms of the candidates they get to this round? The feedback they gave me was almost immediate and was vague about 'a wealth of experience' but 'too conservative' which makes me suspect they thought I was too old (I'm late 40's...). Suspect they gave the role to an internal candidate but I'm annoyed they wasted my time.