As far as I know (I left FB in 2023. worked in FB HR from 2008-2010), Facebook doesn't have a strict target for non-regrettable attrition in the way the Microsoft does (MSFT famously stack ranks the whole company and managers are supposed to manage out the bottom 10%). I would say that Facebook strongly believes that it is healthy to manage people out of the company when it is appropriate and they have always tried to make it possible to manage people out efficiently if it is the right decision (eg, it is not a 9 month process like it is at other places), but they have never forced managers to fire a certain % of employees. Facebook looks at attrition as part of the performance cycle every six months. Like most companies, they divide attrition in to regrettable (people that leave and you didn't want them to) and non-regrettable (people that you wanted to leave) attrition. I believe that the goal was to have non-regrettable attrition be higher than regrettable (%-wise) and that the total of the two should be 5-10% of employees (I believe it is usually closer to 5%). In my experience, I'd say Facebook is actually relatively good at ensuring that people that don't belong at the company are moved out. I say relatively, because regardless of attrition rate, I'm pretty sure that everyone always wishes that poor performers were managed out faster, but relative to other companies in the valley, Facebook does actually fire people (at all levels) and they do it at a healthy rate.