What's the point of mastery anyways? If you are a master software engineer, what does that guarantee? is investing in mastery the best use of your time?
For instance, think about all the skills that a basketball player has to execute in parallel: they have to run around, dribble the basketball, and think about strategic plays, all at the same time. If they had to consciously think about the mechanics of running and dribbling, they would not be able to do both at the same time, and they would not have enough brainspace to think about strategy.
(This comment is basically the intro to a detailed article I wrote on the topic with plenty of scientific citations: https://www.justinmath.com/cognitive-science-of-learning-dev...)
(edit) One thing neither of us directly mentioned in our comments, but which I feel is important is this bit from your article intro:
> Insufficient automaticity, particularly in basic skills, inflates the cognitive load of tasks, making it exceedingly difficult for students to learn
A real-world example for myself was when I was learning a small lick on guitar with an uncomfortable-to-me rhythm. I initially just played it slowly so I could get everything right, trying to speed it up every now and again to check progress. I progressed, but slowly. What ended up demolishing the challenge is the separation of the rhythm element(s) from everything else involved in the lick, and practicing those individually. By themselves they were easy to knock out (matter of minutes), and after those few minutes when I revisited the entire integrated lick I could suddenly knock it out of the park.