I have been involved in a lot of projects, both old and new, and one thing that they have in common is that almost none of them have been using unit testing. I prefer to use it, but often the customer isn´t ready to pay for that, and suppose that the code just works as it should.
So, do you use unit testing in your projects, or do you rely on your coding skills?
Using unit-testing is a coding skill.
I find it adds very little overhead to coding time. On top of that the code produced tends to be much easier to understand and to refactor, with an untold reduction in maintenance time.
A full discussion of the benefits here: Is Unit Testing worth the effort?