the author has just come out with her fiftieth novel. although she published numerous books, her writing style remains tight, with no words.

Prolific, Egocentric, Superfluous

Explanation:

If someone is Prolific, it means that he/she is industrious and highly productive. Or it can be defined as when someone is highly intellectual or intellectually productive.

In the given sentence, the author is prolific as she has published her fiftieth novel.

Egocentric is the personality trait, in which a person is focused on self and do not care for the needs of others. He/she is highly self-centered.

In the given sentence, the author is egocentric.

Superfluous means that a thing is unnecessarily excess, or is more than required. Or, it can also be defined as something that has no useful purpose.

In the given sentence, the writing style of the author is not filled with superfluous words. Meaning, that her writing is simple to understand.