Well of course they do. Because these things are necessary to learning a language. This is the 20% that's most efficient. By definition someone who puts in 100% of the effort will be doing what I did.

The efficiency of this approach revolves around what you don't do. You're excising the 80%. I didn't spend long hours learning katakana, hiragana and kanji. I didn't learn the more complex tenses and conjugations. I didn't spend time on vocabulary words that are highly situational. Contrast this to a typical Japanese textbook.

I'll give a more in depth breakdown soon but for now, I'd probably take a similar approach that I took to learning to read Japanese : learn basic sentence structure, learn top 150ish vocabulary words, avoid books written in non-romaji. Practice hearing spoken word by listening to speeches and following their transcriptions. My exception protocol for unrecognized words was to look them up. And for irregular sentence structure, to guess based on context. It worked for watching movies and reading, mostly but as you can tell, yoi kakikomu koto ga dekimasen*. I'd have to do some thinking on the writing part, it would most likely involve sticking to simple sentences.

*thats terrible Japanese for "I cannot write well". I think. I hope.

Also, when you say "intermediate level language knowledge", what exactly do you mean? One of the key steps is defining exactly what you want to accomplish and why. I don't want to create a whole write-up, only to realize that you and I have two different definitions of "intermediate level language knowledge".

So if you'd tell me the "what" and the "why", I'll do the rest.

Basketball is an example. I'm about to head home so I'll do the ultra-abbreviated TL;DR version:

1. Goals: Score points, prevent opponent from scoring points.
2. Archetypes: Offense (2-point), Offense (3-point), Defense
3. Process How-To: Googled "how to layup", "how to shoot a 3-pointer", and "how to steal a ball" 3a. Process Failure Points: Missing a shot, getting the ball stolen, missing a pass. 3b. Process Difficulties: Anything involving ball handling or dribbling. Defense.
4. Exception Protocol: On offense: Pass the ball to a better player than myself, or set a pick. On defense: play very close to my opponent. 5a. Avoid anything involving dribbling but not scoring. 5b. Prepare and practice two-point shots. 5c. Focus on getting open for a 3-point shot. Practice consistently shooting from 3-point line.
5. Get better by playing.

I would say basketball is fairly complex. One thing I didn't mention in the original post (mainly because it starts to get into the "how do individual people learn") but for me, I don't get good at a competitive skill by competing against people who also suck. By getting good enough to be able to play with people who are actually good, it made it easier for me to learn the advanced part of the game faster.

Also, this post has a list of (at least what I think to be) fairly non-trivial skills that I have trained using this method.

Ha ha, when I first read that, I thought "furriner" was another nickname for Furries and I was very, very confused.

I took your advice as well as estimator's into account and added two paragraphs at the beginning to offer 1. Some research showing that many systems follow a distribution where a small portion of work accounts for a large portion of results, and 2. and explanation as to why it's generalizable.

That's totally fine, like I said, your post made sense and was consistent with what I've seen.

I still don't really think that stating my qualifications would do much. In this context, it still just seems too much like bragging. "I helped build a multi-million dollar company, I compete in barbecue competitions and consistently place in the top 10% of the field and was sponsored by a major barbecue website, was ranked in the top 100 players in the world for a popular collectible card game, learned how to code with no formal education (and used that knowledge wrote a somewhat well-received calibration test, and also write a bunch of boring business platforms), wrote an article about a baseball statistic I co-developed and was published in a publication that's important for people who care about baseball stats, learned how to be a carpenter, at one point was a licensed pharmacy technician, blah blah blah"

Even though I'm sure there's a less crass way to phrase it, to me it still sounds exceedingly arrogant. I might be overreacting though. You tell me: if I prefaced my post with that, would you be more or less inclined to take me seriously?

I do like the idea of explaining why I think the advice works in the first place. I will start writing something up about that and append it to the original post.

Bad editing on my part. Ill update the post and include the original here for posterity

Yup, pretty much. To quote myself

TL;DR: The fastest way to learn new skills is to 1. Break it down into enough "recipes" or "how-to" guides that they cover most of what you might encounter, and 2. Figure out how to eloquently ask for help if you don't know what to do.

(Incidentally, the link you posted does not work, it's giving me a 404).

Articles on such topics are notorious for their average bad quality.

That's interesting, I wasn't aware of that reputation. That's good to know and certainly justifies your skepticism.

All that said, I think one can still evaluate your point (and in my case, my Less Wrong post) based on its internal logic and how consistent it is with one's own observations, without needing research to back it up. It would be easy enough to dismiss your own post for the very reasons you cited. Consider the following:

"In general, people new to a community are notoriously bad at gauging the pulse of said community. To reformulate in Bayesian terms, based on the length of time you've been posting here, the prior probability of your statement being true is low, so shouldn't you provide some proofs or evidence -- or why should I (or anyone) believe you?"

But to me, your logic checks out, and is fairly consistent with my own observations (that most self-help publications tend to be garbage), so that shifts the probabilities significantly in your favor. I'm hoping that people will evaluate my own post by similar criteria, rather than immediately dismissing it.