no, it's just what happens with any process; as you gain more experience with it, you learn more about it, so you can get more and more controlled results
For a glimpse at how they do things, see this fascinating talk: https://www.youtube.com/watch?v=NGFhc8R_uO4
You'd be surprised. My personal knowledge of one major fab is that they have policies such as regular rotation of employees which make it difficult to maintain institutional knowledge. I have heard complaints from multiple people of their teammates and managers "winging it" to think it's isolated incidents.