I don't think so.
I think knowing vocabulary is much more improtant when we want to speak English fluently.
Of course, knowing vocabulary doesn't mean we have to memorize them as many as possible.
The priority is to know how to use vocabularies which we're often using in actual situations.
That is, we focus on memorizing and practicing in actual situations.
Another point is to understant = understand  its accent.
We have to study how to be pronounced and how to be changed in the sentences.