High quality tightly coupled code tends to need less testing because it's tiny in comparison. I have seen plenty of cases where throw away code was less than 1

High quality tightly coupled code tends to need less testing because it's tiny in comparison. I have seen plenty of cases where throw away code was less than 10 lines be replaced with 10-100x as much "reusable" code that without adding any end user related flexibility or improving performance in any way. PS: I once wrote a 4 line hack in under 30 minutes for another team. They re-factored it into 12 classes over the course of a month and zero functionality was added. So, sure it was ugly and hard to write test cases for but they still put it into production to fix a major bug.