Valuable writing
Note
This is all stolen or paraphrased from the video LEADERSHIP LAB: The Craft of Writing Effectively by Larry McEnerney, which is also recommended in our Improving your writing page.
People often focus on rules when defining good writing. They say things like "Is it clear?", or "is it persuasive?" But the only thing that really matters is, "is your writing valuable?" Some writing is, and some isn't.
That's not saying that the rules aren't important. Your writing needs to be clear. It needs to be organized and it needs to be persuasive. These are probably the rules that your teacher focused on.
But it’s much more important that your writing is valued by the reader. Often the person reviewing your writing is your boss or your editor or your client, and often you can get caught up trying to make sure that that person is happy with it. But normally they aren't the person who is going to get value out of it, and you need to continually remind yourself of who the real audience is.
People will still read valuable writing that is not clear and not organized and not persuasive. But if your writing has all of that and it’s useless then overall it’s still useless. So when reviewing your writing, ask after every sentence "is this valuable?" Once you've got a valuable piece of writing, you can always add clarity, but the opposite is a lot harder.