> Though, there are always workarounds when managers want to keep their highest performers off the list.

Never assume you are safe. I was a single point of failure on a team that was supposed to be revving up for some pretty important strategic initiatives. My manager put me on a “do not fire” list prior to the company conducting a layoff of 30% of the company last fall. Still got canned. My manager went tried to determine why I had been let go when he specifically indicated I was a single point of failure . Turns out, it was because someone in HR had mixed up some spreadsheets :/