I certainly think that having a firmer understanding of the tools at your disposal can improve your workflow. As a Clip Studio user myself, I've naturally changed defaults and reworked a few brushes as I've gotten time to analyze and understand my workflow in the program.
That being said, no tool by itself can improve art, improvement only comes with experience. It's not enough to have a tool, you have to understand why and when it's useful, and how to use it most effectively - and this depends completely on the individual.
One of the best examples I cite for this is screen tones. Putting screen tones down in digital is more convenient than in analogue, which is in turn probably more convenient than drawing the pattern by hand. However, your effectiveness in using any of these is restricted by your attention to detail - if you don't understand that a pattern on a piece of cloth will be affected by how it bends. or if you don't know how to emulate such an effect, screen tones will conserve time, but they will not improve the quality of the work. And in turn, someone who uses screen tones and understands these principles will more than likely be able to emulate the affect in analogue, even if it is more time consuming.
With all that out of the way, I reckon you should hold off on buying any additional materials for now. Experience (both with drawing in general and using a specific tool/program) are most important, and they take time to garner.
Who knows, after a while you may get to understand your own needs better and make a few custom brushes that are tailored to your needs far better than what you would have bought in the first place 