It can be the very best tool sometimes. If you have a property to test, or if you have an oracle, or a brute force method. For example you want to refactor a complex method. Just take a copy of that method in the tests as the oracle and set up a Sample test so that they always agree and refactor away. You can also put a Faster test on it at the same time and prove it's 3x faster say. It's just more robust than a few examples.