So not an actual metric beyond opinion and anecdotal. Hard to discuss a number and your follow on points when you have nothing factual to back it up with. I’m not saying there isn’t dead weight. My experience also anecdotal in 3 different departments is like anywhere else you have 10% of your people that take up 90% of your time. On any team I’ve been on there have been some underperformers. But nowhere near the made up numbers you are providing. I’ll accept that it’s hyperbolic or at least concede that where ever you worked in the PS that it was probably a really bad place.It's not a stat / not meant to be strictly literal. It's from my earlier post where I quipped that the public sector is a place where 5% of the people do 95% of the work. It's a play off of Price's Law, except my personal experience says in government it's much worse.
The issue with the deadweight for me is no one deals with them. They tend to move on before anything is done, get promoted out or just get shuffled off to be someone else’s problem. Most of us with any real time in the PS or CAF has seen this a few times.