Hired-to-ramped is one of Heidi's workflows: new hires get the company's memory from day one, so ramp stops depending on tribal knowledge. And when people leave, what they knew stays.
A new hire asking 'why do we do it this way?' gets the actual decision with its source instead of a shrug. That compresses ramp time in a way no wiki ever has, because the answers are alive and current.
The other direction matters just as much: departures stop deleting institutional knowledge.