These people have their experience in one field for all these years, therefore they know a lot about it. They also work with limited number of technologies, which makes them good in them.

So, basically, they are good in certain tasks, so as long as they do these tasks you won't notice their lack of experience in other stuff.

> any skills/traits in those people

There are no patterns, to be honest, otherwise everybody would do it. There are best practices (some of them are debatable, like mentioned TDD) which you can read and try to incorporate, but don't treat them as dogmas.

Solve challenging tasks, reflect on your code, try different stuff, actively talk and discuss solutions with more experienced engineers, and you'll learn (relatively) quickly.