I'm not a strict TDD follower, yet a byproduct of my development process leaves me with unittests. They give me confidence that the code I just wrote behaves the way I want it, and deleting them after that just ensure that refactoring isn't on the table without a significant time investment.

The drawback of this, is that the test suit grow fast, and need to me groomed pretty often, but it's a fair price to pay and in the end it's faster for me, and produce far less bugs.