> This mindset fails to take into consideration the fact that tightly coupled things are often simpler to understand and reason about You're right on a small s

> This mindset fails to take into consideration the fact that tightly coupled things are often simpler to understand and reason about You're right on a small scale. With teams or feature changes, tightly coupled things quickly breed incidental complexity. I like what you said about decoupling not being unqualified positive. It's not, it's very good, but it's costly (with a high return). It's all about trade offs. Testing, and specifically testing-first, is expensive compared. If I'm working on a critical piece of my system? Yep, worth it. TDD. Do I need to refactor something so I can reduce complexity with this change? TDD. Am I writing a quick workaround for better UX that will be removed after two days? TDD isn't appropriate. It's a essential skill to have, but not the only way to practice.