This particular code serves me well (in my consulting efforts) since 2008 and 2011. As for maintainability, I still clearly understand it and it can be immediately used everywhere.

If, by maintainability, you mean "looking at the mess I did some years ago in some large project and see how it turned out", then yes, I avoided such projects and large teams. Most of my code was written either by me alone or as a part of 2-3 persons team.