Some serious benefits:

• You’ll get to know your own writing habits better
• You’ll develop writerly discipline
• You’ll stick around long enough for new ideas to occur to you

Study your words on multiple levels:

• The lexical level, i.e. specific verbs, adverbs or adjectives you might be repeating (are your characters constantly grinning?);
• The sentence structure level, like if all your examples come in threes;
• The narrative structure level, like if you unwittingly but consistently lapse into new flashbacks.

“The real importance of reading is that it creates an ease and intimacy with the process of writing; one comes to the country of the writer with one's papers and identification pretty much in order.”

Look closely at how the other writer avoids repetition and regulates sentence length, and become aware of all the words that could’ve gone into the sentence, but were trimmed out.

Experimentation seems to be working for George R.R. Martin, who has for decades been writing short stories, novellas and even reference books between instalments of his novel series A Song of Ice and Fire

As you edit your work, you’ll be thinking of what you intended to say at the time of writing.

Learning about story structure and the different models that dramatists and fiction writers rely on, like Freytag’s pyramid or the classic three-act structure, is valuable for any aspiring writer.