You can’t go deeply into everything. In many cases it will be a more rudimentary level of understanding and experience which is there to support your speciality. And then over time you get deeper and deeper into those things as you gain more experience with them. I’m sure you’ve heard the term “t-shaped” before. Visual design may remain the one area of expertise where you have a really deep understanding, but it’s good to know enough about a lot of other aspects so that you can broaden your skill set with things that support your main skills.