And, most important, do you test as you go, or have you become so good that you don't make silly little mistakes such as misplaces punctuation and the like?
A lot will depend on how "expensive" tests are. The price of a testset comes two ways: creating the testset, and running it. Take for instance the early stages of your new project. After writing the first bits and pieces, you don't have anything yet that can stand on its own. If you want to test the bits of pieces, you may have to create a lot of scaffolding to get your bits and pieces running this makes creating the test suite relatively more expensive - and so does running, since each failed test needs to be examined, was it a bug in the bits and pieces, or did the scaffolding fail? And if your test involves smashing a $100,000 dollar car against a concrete wall, it does make sense to limit the number of test runs as much as possible.
Like everything in programming practices: it's a trade-off.
