You'll see a theme in history - armies that train for "worst case scenario" eventually kick the hell out of armies they don't. Command and control based armies, that only fight well in formation, tend to do really well until their ranks get broken. Then they get slaughtered.
If you look at George Washington or Napoleon Bonaparte, their forces knew how to fight out of formation. That's why they were able to win important battles against larger, more well-equipped forces. They stirred up a bunch of chaos because their forces were able to handle chaos better than the enemy.
I think if you want to do creative endeavors like writing, painting, whatever - you need to learn to fight out of formation. By that, I mean you need to learn how to do it without having "formal expert tone" or being highly polished. Ideally, you can communicate well without necessarily obeying grammar and punctuation. After all, the point of writing is to communicate - the language is supposed to serve you, you're not supposed to serve it.
It takes a lot longer to get into formation if you're out of it than to just fight slightly wild and crazy. Of course, you should learn discipline and how to fight in formation, and should be able to do well in that role. It might even be your bread and butter. But if you're editing every memo you send, every blog post you write, every rallying talk or speech you give - then you're burning a lot of time.
Yes, fighting in formation produces better results much of the time. But sometimes ranks get broken, and then you're screwed if it's the only way you know. I think it's better to learn to fight out of formation before you ever need to. The quality of out-of-formation output is going to be lower at first than in-formation output. You need to learn how to deal with a chaotic messy environment. It doesn't have to be the only way you do things; in fact, sometimes you ought to use proper grammar and punctuation. But you also should be able to handle not doing it, just throwing things together with commas and dashes, slapping some rough thoughts down, and figuring it'll turn out okay. As long as what you're saying is clear enough, you don't have to bow to formality.
I'd say this is probably true in any discipline that doesn't have life-and-death consequences - there's a highest level, most correct way of doing things. That way produces better results, and is superior if you're in the right frame of mind and environment to do it.
But sometimes you're not in the frame right of mind, or you're in the wrong environment, and you don't have enough time to form up. In that case, much better to just bang something out and run with it. And if you make a habit of learning to fight out of formation, you get better at it, and can do it more and more over time.