Beautiful writing is like salt and paper.
If there is not enough - the food is bland.
If there is perfect amount - you wont notice it.
If there is just a little bit more than there should be - you will instantly notice it and might say:
"Oh, that's interesting! Quite spicy, huh?"
If there is way more than enough, you will put the food aside because it is inedible.
No matter what type of fiction you write, beautiful writing must always be present.
How much should you use? Well, that's up to your taste.