There is a lot of better applications broaden vocabulary and increasing your language skill. That app is not about that, it’s made for passing tests and exams. If you don’t want to broaden your vocabulary in some topic, you don’t want to learn some new words but you’d like to pass exam from foreign language, that app is perfect for you.
You’d like to learn specific set of words, no more, no less, just what teachers demands from you.
Why you would waste time for repeating random words from “animals” set when your teacher demands only cat, dog and fish to pass exam.
You add words, you repeat , you pass, you chill.