I can see how TDD could be useful for writing a relatively static piece of code, especially code that is likely to be reused by a lot of people.

But I develop web applications in 1-week sprints for my stakeholders and they're likely to change their mind about what they want at short notice.

In these circumstances it simply doesn't make sense to write tests up front. I don't even have time to write a lot of tests when I'm done :-(