I've been studying Japanese for 10 years. That means learning and retaining thousands of characters, terms, pitch accents, multiple readings (about 2-10 per character), stroke orders, components of characters, example sentences, levels of politeness, etc.
He says one shouldn't just repeatedly look at the information, but quiz oneself. Even in school, as inefficient as our education system is, I wasn't told to just reportedly read the information. Instead, one should cover one part and guess it, so to speak. The whole spaced repetition aspect seems to be missing in this article however, and it also was missing in school, since you'd mostly be able to forget about things after the exam.
Looking at the penny example he seems to suggest that I should study the character 犬 by putting 太 next to it and ask "which one means dog?". I think this will only make you better at multiple choice tests and confuse you because you conflate unrelated knowledge with each other.