[hitchdev]

It's not purely about skill, code quality also improves as a function of discipline, a willingness to take risks and outside pressure.

fwiw I dont think Ive ever seen clean code that didnt make use of something at the very least resembling both exhaustive CI/CD and TDD. There are some practices which are basically essential even if some of the mavens of "best" practices mistakenly label a few that arent necessary as necessary.

[gregjor]

Can you define and measure "code quality?" If not how can you say it improves?

Even granting your point, the things you list that supposedly improve code quality -- discipline, taking risks -- come under the "skills" heading in my understanding.

> I dont think Ive ever seen clean code that didnt make use of something at the very least resembling both exhaustive CI/CD and TDD

Yet almost all of the code ever written, including very successful long-lived things like Unix, the C standard library, Oracle, etc. got written before CI/CD and TDD. I don't have a definition of "clean code" to judge by, but I have certainly worked on lots of readable and maintainable code that did not come from TDD or CI/CD processes.