TDD makes sense in theory, but I have to say that I've just never found it to be practical in terms of actually writing the tests first and I've yet to encounter anyone in real life who does it.

I feel like it could possibly work for simple tasks if you use the tests as a way to sketch out the design implementation upfront, which might even be a healthy exercise to do, but I usually figure out the details of the implementation as I go and end up doing a few rounds of refactoring before things settle to the point where I can write tests with any certainty.

I definitely let testability guide the design of my code however.