Parents and teachers often tell students to "add more details" when commenting on student writing.
It's one of the least helpful things that you can say to a writer.
Have you ever finished a novel or essay or memoir and wished that the author had included "more details?"
Teachers and parents say this to students because so many of them are not writers and do not seriously engage in the writing process. As a result, they simply don't know what to say in the same way I could say nothing to a apprentice carpenter or a beginning skier.
If you don't engage in the craft, you will have little to say about the craft.
So rather than talking about craft, parents and teachers see quantity as quality. They believe - with all their heart - that an argument that be effectively made in 250 words is automatically made more effective if written with 500 or 1,000 words.
It makes me insane.
To this end, young writers should remember this:
Don't seek quantity. Seek quality. Rather than waxing on for paragraphs about a person or place, find the two or three words or phrases that capture the essence of the person or place, and leave it at that.
The best writers don't choose the most words. They choose the right words.