But this advice should be extended further. Always be willing to throw away the code and the tests. Take the learning.

Be ware, though, that you are not throwing your customers for a bad ride. As soon as you have customers, it is nigh impossible to throw away the code without neglecting them. And they are your ultimate responsibility. Not the code.

Exactly right, it can be very hard to make changes (even the right changes) once it's in customer hands. Sometimes it is easy, sometimes it is not. However, it's always easy to throw out code that isn't yet committed.