When we first start training a new skill, it's very cerebral, meaning that we're doing a lot of conscious thinking about how it works while executing it. This raises the cognitive load (https://lib.hol.ink/index.php?topic=31.0) involved in executing any tasks that utilize this skill. It also makes it much slower to use. To avoid that, we aim to reach a point of automaticity in the skill: we want to be able to execute it unconsciously without a significant reduction in accuracy.
Of course, there will always be some loss of accuracy when executing something automatically. Consider touch typing. You're always going to hit the incorrect key every now and again no matter how good you get at it. However, the speed gains and cognitive freedom involved in touch typing eventually outweigh the loss of accuracy.
Note that "eventually." When you first get started touch typing, you're so inaccurate that you're actually even slower than you were when hunt-and-pecking, if one accounts for the error correction time. This often causes people to give up on that automatic training. It doesn't seem necessary, and nobody has the time for all that, right?
But skipping that training then makes every task that involves typing that much more difficult. Suddenly, taking notes or writing essays is some deep cerebral process, merely because you're not a strong enough typist for the keyboard to be an extension of your body yet. You're forced to put your attention towards the typing process instead of the content of the work you need to perform.
As artists, this issue is a constant source of conflict. Training feels dumb, and you see these complex procedures that take a long time, and all your professional artist friends insist they never do it like that in reality. They don't even remember learning it.
But without training those skills and concepts, you're missing prerequisites needed to work without them, and no amount of practice is going to make the process less stressful. And because your baseline stress level associated with art is heightened from this, every other work or training task you do utilizing the skill is that much more stressful, causing you to abandon projects or drop out of classes without understanding why others can keep up with what you can't.
Automaticity is extremely important in art. Not because it makes you look cool, but because it enables you to go further in your studies and workloads without burning out. It also enables the use of automatism (https://lib.hol.ink/index.php?topic=41.0)-based workflows with fairly consistent output quality.
Unfortunately, a lot of programs out there these days try to train "intuitive drawing" without actually scaffolding you up through understanding each skill and making them automatic in a logical order, which can leave students grinding for years at the big picture solution with very little progress.
So I want you to come away from this post realizing that automaticity is achieved in the little things, not the big ones. Yes, lots of little skills can contribute to being able to use an automatic approach overall for very relaxed sketching. But if we imagine that you're reading a drawing textbook, automaticity is something you start training after each sentence or paragraph mentioning a technique or concept, not after each chapter or when you're done reading it.
Practice a little thing until it's not deeply stressful nor intimidating, then practice the next little thing, combining it with the last one. When that one's not too stressful, start practicing the next little thing, combininig it with the last two... Eventually, the previous little things become so automatic you may entirely forget how they work and still get it right 99% of the time.