Well yes, if we could only train new employees for 20 years in the specific curricula of the organization, as that is how long we spend getting pi and calculus into the heads of kids.
On the scale of lifetimes, I don't think we can refer to it as "churn" as understood in the context of a modern company.
I'm being facile, of course. Developing a good library of knowledge as you propose is hard, takes a long time and many iterations and there is the unfortunate matter of time taking it's toll on the relevance of such recorded knowledge (esp. in our line of work). Not to mention costs. Even academic institutions, who are in the business of doing exactly this, guard their staff with tenure (some of the staff anyway, the big boys)
It takes 20 years because kids come from all kinds of backgrounds and there isn't enough funding for individualized support. A company should be able to get someone up to speed faster since that person is presumably chosen for that role based on existing proficiency. It's easier to piece together an understanding of the system from the napkin scratch notes of the person who got hit by a bus than it is to hope they come out of the coma before the business fails. Imperfect documentation is better than none.
We are not in disagreement here. I was making a comparison in kind as a cheap rhetoric trick. Documentation is good, no documentation bad, good documentation can be better.
Slide along the scale towards more and better documentation and our perceptions might diverge. I don't think all the valuable know-how that goes in to fulfilling a specific role in a larger organization (and in particular the marginal knowledge, relations and skill that increases performance) can be captured in words. Even if it were, there is so much of it and it is full of subtle nuance and context sensitivity. On top of that each individual person takes to different parts of it in different ways. The things you can only learn by jumping in at the deep end. We all know, deep inside, that this is the stuff that matters and I see no reason to play charades and pretend we can know or see how even half of what we do really works. If we did, the world would be a very different place. Until then: tacit, implicit, context bound and relation contingent knowledge and skill will be the light that shines on our practice; and what we can put in to words, a mere shadow.
On the scale of lifetimes, I don't think we can refer to it as "churn" as understood in the context of a modern company.
I'm being facile, of course. Developing a good library of knowledge as you propose is hard, takes a long time and many iterations and there is the unfortunate matter of time taking it's toll on the relevance of such recorded knowledge (esp. in our line of work). Not to mention costs. Even academic institutions, who are in the business of doing exactly this, guard their staff with tenure (some of the staff anyway, the big boys)