[westoque]

i've worked on many legacy code bases and i think an underrated skill that you need is courage.

courage to be able to push changes you think could be breaking changes but always be optimistic that you to be able to fix as soon as possible. tests are ideal, but not everyone has 100% coverage. sometimes you just have to trust your gut and do diligence and push the change. don't be scared to push something because you don't know the behavior in production. the only way to know is to try.

[juangacovas]

Agree. But you need confidence on being able to debug / log / fix / revert, so having a strong knowledge of some of the parts is mandatory (i.e. server if it's web-dev, etc).