quality over quantity
An implication to that an essay, for example, does not have to be 20 pages long if it's full of bullshit. Rather a short high-quality essay than a useless high-quantity essay.
Example:
Remember class, Quality over quantity on this paper. There's no need to write a long paper if it's filled with pointless sentences.
Remember class, Quality over quantity on this paper. There's no need to write a long paper if it's filled with pointless sentences.