[maxxxxx]

You can also write "Methodology X doesn't work always". All methodologies work well for some situation and for others they don't. In my view TDD is great for a lot simple things and algorithms and you can structure your code in a way that most of the code is inherently testable. But when things are so complex that you don't even know the correct architecture upfront, TDD is a killer.

[spronkey]

If things are that complex, sounds like you need to be doing some discovery work (spikes) first to break the problem down. Then you can use TDD again :-D. So, I guess you're right - if you don't know wtf you're supposed to be doing, TDD is a killer. But then, so is anything else.