As in photography, archery or karate, focus is an excellent tool for writing. Focusing in on the subject matter can give an essay deeper meaning. It can give a poem instant revelation. It can give a character back story or an essay immediacy.
The smaller the moment you’re writing about, the better the opportunity for description and the richer the experience for your reader. I tell my writing students to write about a single moment–a first kiss, their first time driving a car, the first time they swam underwater–to exercise focus. Instead of writing a narrative about a family vacation or falling in love, topics that require scene after scene after scene, writing about a single moment for 3-4 pages allows a writer to slow down and recreate all the sensations of that particular moment.
Writing with singular focus, whether in a poem, story, essay or novel chapter, can help a writer mine out the best gems. Try it!