The worst thing in a codebase is coupling

The worst thing in a codebase… is coupling.

You can have modules that are a bit rotten inside: if they are well separated and have clear interfaces, you’ll be fine.

On the other hand, if they are much “better” (fast, optimised…) but coupled to each other in every direction, everything will very quickly turn into an unmaintainable hell.

Don’t get your priorities wrong.

Untangling that kind of coupling is a good share of my work.