How you learn 4 languages at the same time

Language experts like Theodor Lewandowski have come to the conclusion that just 1,000 words of a language are enough to understand 85% of the language. Approximately 2,000 words are required to understand 90% and 4,000 words to understand 95%.
Therefore, it makes sense to memorize the 1,000 most common words first so you have a solid foundation on which to build.
Many language schools, compulsory schools (including grammar schools) and also learning apps usually do not recommend their students to learn the 1,000 most common words first, but rather concentrate on very unrealistic vocabulary that rarely appear in real life .
And so it is no wonder that even after many years of language lessons, many students still cannot understand 20% of a text, let alone speak or write.