It depends on the situation but using it as a primary method is probably not effective at all.
As stated by ettanany, you will get bored very quickly. Sure, you will probably be able to learn a little more but it is overall not very efficient. Sanity-wise, you will probably abandon this method in about a day. Honestly, it would be best to use sentences to learn your nouns, verbs, adverbs, etc.
Why sentences? Well, they're everywhere! In movies, books, poems, stories, videos, and even this answer (shocking isn't it)! When learning to improve upon one lexical class, try to focus only on that class when reading or writing or watching a video. For example, let's say you just read this sentence:
The man said that he was willing to kill the woman later that evening.
You can focus on:
Nouns and pronouns - Pronoun and antecedent agreement (i.e. agree in gender, quantity), Subject-Verb agreement (agree in quantity, etc.)
Verbs - Again, subject and verb agreement, tense (past, future, present) and type (simple, progressive, perfect)
and more but the above are the most obvious. Now looking at just one class is fine, but through one class, you can learn more about another.
Let's say you are currently focusing on nouns. You would notice that the first noun is "man" which does the action of speaking in simple past tense of speaking, "said". "said" has to agree with the subject, "man", in able for the sentence to be correct. Now you see the pronoun "he", which has to agree with the subject, "man", by quantity (one person) and gender (male) and so on.
Thus it is not beneficial to learn by a single class since you will actually learn multiple at the same time anyways if you really want to understand how each class works and interacts with each other.