I've been composing for almost 3 decades!, hell, I'm still learning new stuff almost every day. That's what being creative is, figuring out how to make your craft as best you can. The more you do, the more you learn.
All the areas you can improve on if you're not progressing in any other one area for some reason is.
11. Musical Analysis
It's a little like an RPG game, you need to level up all your musical skills to obtain "Epic Composer" title.
I've made music with not very professional sounding sounds to begin with, but knowing how to polish them up to sound good and use them in a mix will instantly increase your quality meta score.
I recently used really old instrument samples taken from all sorts of old equipment back in the day of SNES, N64, Dreamcast but preformed quite a bit of sound design and mastering on them to make them sound shiny and modern to give the game a retro throwback but with better production.