By a very large margin, for most of the time you are actively developing as a full time employee at a large tech company, you're working on integrating systems, either through a build language or extending your software to use an already existing API.
What are the most useful skills for these tasks? Being able to communicate effectively, feeling comfortable asking questions, feeling comfortable admitting when you don't understand something, and being kind and friendly with those you interact with.
Therefore, when interviewing new hires, I do not ask many technical questions beyond a general competency question.