The idea of 'becoming good at something artistic takes a long time' is misleading. The more important thing, I would say, is to learn to tell what elements are more important, and where to focus your efforts. In other words, really understanding the fundamentals for whatever practice. Art, as a casual sort of definition, is arrangement of elements to some intent. Or, art is design, in other words. Since all art follows the same principle of design, the hours invested into a specific discipline of art consists only of mapping specifics to the understood fundamental, and learning whatever amount of rote knowledge is needed. For example, contrast in painting can be expressed in hue, value, and the characteristics of edges, and in music by pitch, timbre, dynamics, etc. Having some understanding of the idea that varying the characteristics of some element can produce a pleasing affect (contrast), we can express it through varying it through the more specific qualities of the art. But you can't just wantonly apply 'contrast' all over the place, you'll end up with a horrible mess. And this is where the real understanding or lack of in the fundamental will show, in the expression of that quality at higher levels of abstraction. It's generally obvious that you might make a song by plonking out a few notes that differ in pitch, and perhaps they shouldn't all be evenly distributed in rhythm, but even making that much sound 'good' can be quite hard, to say nothing of motifs or larger themes. In short, the bulk of being 'good' at art is being able to express your intent better because all decisions to the arrangement derive from the intent. Knowing your intent and the tools available to express it, any particular artistic form of expression is a matter of 'translation', adapting to the local forms. So that's some thought about 'mapping specifics to understood fundamentals', but what about 'rote knowledge'? This is just the sort of stuff intrinsic to the art, that is, whatever understanding of fundamentals does not include. If you want to draw non-malformed people, an amount of superficial anatomy knowledge is necessary. For composing western tonal music, knowing the keys, the grand staff, and some ability to read musical notation is very helpful. You probably want to be able to play an instrument tolerably well in addition, and no amount of knowledge about 'contrast' is going to do anything for you in that respect. But rote knowledge is very learnable with some amount of consistency, and certainly is not any sort of lifetime pursuit, hence its name. So the two together should comprise entirely our learning of a particular artistic discipline, and should take much less than, 10k hours say, or at least a 'very long time'. This means that our ability in an artistic practice should be limited by our understanding of the fundamental traits, rather than specifics. And almost always the practice itself will be the tool for how we refine our sense of fundamentals, but it's an important distinction between viewing that as only practicing the specifics of one artistic discipline, and learning at a deeper level. Naturally, some practices are more related than others, and those more related arts will share more 'concepts'. Take for example, the case of sculpture and drawing, where gesture and anatomy as 'fundamentals' are requisite in both. A 'fundamental' is just some common pattern in a discipline. Hence, all art shares the fundamental of 'design', that is, communicating intent, some arts share the concept of narrative pacing, and few have the concept of neat stitching. To talk briefly about my individual situation, I've spent ~4k hours on physical drawing in my life and ~1600 hours on digital art. I believe that a good majority of that time was redundant, that I wasn't actually thinking about what was important. Contributing is the fact that I was in middle school and under for at least 2k of that, where I am dubious of being in any sort of position for learning anything signficant, intuitively or otherwise. Having the somewhat more distilled ideas of what's important and not, I think I could recover my current level in a fraction of that time, if I had to relearn everything specific to the practice.