Learning a language is often a painful process. Most people get to the point where they learn some basic phrases and words, and then stop trying. This 10-30 Word for Word method tries to get people to learn all of the language, in a relatively easy way. Learning a whole language is only possible through reading, conversational skills get you only so far. If you have experience reading a foreign language, you'll know how the foreign words start to buzz around in your head already after some regular reading. You're absorbing the language as you read. Adding audio to the text will make sure you can also understand spoken language.
10-30
When learning a language, on average you have to "meet" a new word 10 to 30 times over a certain period to memorize it. Cramming will not serve your memory in the long term, so it's better to spread out the "meets" over a longer period. Overall, learning words from lists is boring and unnecessary, when you can learn them just by meeting them enough times in a story.
When reading in a foreign language, you will meet certain words again and again. Ultra high frequency words such as articles and pronouns will be met, and learned, in the first chapter. Regular high frequency words such as certain verbs or nouns will also be learned pretty fast. Once you learn to recognize roots, you'll meet them in other verbs or nouns, giving you an edge in memorizing those faster as well.
That leaves you with the low frequency words that have no obvious root form. For those words, just revisiting them over a longer period of time is enough to memorize them as well. Especially when learned in the associative context of a story.
Word for Word
When learning a language through a regular course, often words are learned alongside artificial short texts and some grammar. Although you might have been taught otherwise, this is not a natural way of learning. Young kids learn language through hearing words, and the more and the more diverse the better. Naturally for learning a language as an adult goes the same. The more words the better, don't dumb it down. Graded readers exist because they are designed for a certain student's vocabulary level. If there are too many unknown words, you can't read the text.
This brings me to the bit "Word for Word" of this method. The literature or stories that are used in the "10-30 Word for Word Re-reading" method ALL have EVERY SINGLE WORD translated, either in interlinear, interlinear-on-demand or pop-up format. This means that there's no lookup time. Learning a thousand different words, through generic re-reading or re-reading the specific paragraph or sentence where a rare word occurs, and meeting them 15 times, would cost you just the time it costs to re-read the story or specific sentence. That is much much shorter than learning the same amount of words with a course where words have to be practiced separately, or with graded readers where unknown words have to be looked up in an index, causing you to spend for example one minute on each word each time you have to look it up again.
Re-reading
Re-reading texts is based on ancient methods. Oral tradition existed for thousands of years before people started to write things down. And even then people learn these texts by re-reading them, look for example at the huge religious texts in Arabic, Hebrew, Greek or Latin that were rote-learned by non-native speakers!
As explained above, when re-reading you're encountering words naturally. On top of that you're also learning the structure of the language in a more natural and thorough way than with some artificial short texts in a course, or by cramming word lists.
If you try re-reading foreign language texts that have every word translated so the meaning is immediately available in interlinear or pop-up format, you'll notice that after a few re-reads you already are mastering a lot of the words in the texts, simply by "meeting" them in a natural way.
Summary
If re-reading texts with interlinear translation is the key to learning very difficult "classical" languages, why should we not apply it to more "easy" ones? Well, for one because there's no material. That's what we try to change by creating interlinear stories in modern languages. And that's where you come in by buying it and supporting the creation of more of them.