My team and I have been going through a few rounds of documentation efforts. You might ask why are we doing multiple rounds? I really don't know why, but every single effort get "completed", dumped on a share that no one really knows where, and the documentation expert, typically a vendor, moved on from this project, and we're back to square one after a few months.
One of the things that I've been constantly fighting a battle with my former manager was the fact that a lot of the things that i'm doing is hard to document down. It's also something that he, and other folks, have labeled as "tribal knowledge".
On one hand, i understand the need to have some baseline of knowledge; on the other hand, it is a challenge to provide an almost infinite amount of variables in a system that doesn't necessarily reproduce the same issues every time you try to do so. So what happens is that I'll offer to show people how i think, in the mind set that you train others to fish, and not just hook a single kind of fish.
There's no way this monkey in Japan could have been reading up documentation before he start serving customers in the restaurant.
Documentation doesn't mean nothing if one doesn't understand!