@timbray
This brings to mind the section of the 1982 Adm. Grace Hopper lecture (then Capt.) about a mathematical treatment of analyzing code change propagation.

Starts here:
youtu.be/AW7ZHpKuqZg?t=938

and in particular here
youtu.be/AW7ZHpKuqZg?t=1072

where she talks about the system never stabilizing.

Of course the answer is to lock down the inter-module interfaces and subject them to a more rigorous change management. Hard to do with wild-west libraries.