I've been wanting to try this approach for learning a language. In English for example, learning the 800 most common words, you can understand 75% of the language: https://www.bbc.com/news/world-44569277 . I'd love to start fresh on a new language, take 800 new words, try to learn 10 a day, and see where I get after 3 months. Can I really understand 75% of text if I have perfect recall of those 800 words?
You need a lot of input before you’ll understand 75% of the text in a language. Vocabulary flashcards (preferably with audio) can help make some very simple dialogues or stories comprehensible at the beginning but flashcards are not enough for learning a language.