Yes. I write lots of unit tests, but they are mostly part of the coding process: I find they are superior to the manual testing I would have to do otherwise

Yes. I write lots of unit tests, but they are mostly part of the coding process: I find they are superior to the manual testing I would have to do otherwise every time I add new code. But as long term protections against regressions, such tests are less valuable than more coarse-grained integration tests.