I one worked on a commercial product, a mix of C++ calling our own C libraries, that had 4000+ LOC in a single case statement. This was one of my first jobs out of school so I was shocked.

My experience reading lower level languages suggests me that this is not only possible but it seems that the higher the quality of the project (in scope, authors, products) the more of those you find.

When people focus on the _right_ implementation for _their_ problem they often find out that best practices like DRY or abstractions don't scale well at all.