Although it is important for students to think about focus before they begin writing, focus can also be strengthened through thoughtful revision.
“The goal of revising is change. The word “revise” comes from Latin words that mean “to see again.” So in a revision, you are seeing your text or story or document differently, and making changes that move it from its current state closer to that new and different vision. Revising often involves making large, sweeping changes, reorganizing part or all of the text, significantly adjusting tone and voice, and/or adding and removing sizeable amounts of material as well as fixing grammatical issues. A well-revised text often looks and sounds very different than it started because it now says something much closer to what you really want it to say.”
James M. Ranson, Wall Street Journal bestselling editor and ghostwriter
It is advantageous to think of revising and editing as two distinct practices. They do cross, but essentially, revision is a recurrent process of writing and re-writing whereas editing focuses more on stylistic and grammatical facts once you have a satisfactory draft.