Thanks for writing about this topic, Johnathan! It’s definitely good to have more conversation around this.
We have an unlimited vacation or “flexible time off” policy at Khan Academy. We do state right in people’s offer letters that we have a minimum of 10 days vacation required per year. We’ve also been working on explicit guidance around what is typical and want managers to be aware of how much vacation their reports have taken so that they can encourage more.
Having recently hired people who had vacations already planned for soon after their start dates, I find the lack of formal accounting around our unlimited vacation to be nice for everyone in those particular instances. Not having to think about accrual during a year and things of that nature is really nice generally.
That said, I’m in total agreement with you that without guidance and encouragement from managers, unlimited vacation could mean minimal vacation. People tend to take too little vacation in the US as it is (I don’t know how it is in Canada), so making sure that people have a healthy amount of refresh regularly is important!