[mschuster91]

> Usually only the minimal amount of work will be done to get an integration to work, skipping the refactoring or code changes to internal data structures or algorithms, so the “new” product will be the sum of its parts also from a resource consumption point of view.

This describes Atlassian stuff just perfectly.

> As the code base gets large, bugs will creep in and become harder to fix.

And this is why automated tests - even if it's "just" end-to-end functional tests - are so important. But most managers aren't willing to give developers the extra budget do set up proper testcases...