When we think of getting better, we tend to focus on what we do. Learn Photoshop/SQL/PowerPoint, etc.
While focusing on what we do adds a lot of value in the short term, I would contend that the majority of the value in the long term lies in our ability to improve how we do things. Learning to structure problems/design a life that maximizes focus and intensity/be more productive/learn all have huge long term impact.
Sure, go for that skills upgrade. It is probably on your mind because it is urgent.
But, don’t forget the important stuff just because immediate returns can’t be easily measured.