So I'm going to piggyback off of _refugee_'s post because this is opportune, and because I kind of disagree with it.
The problem is there are two kinds of writing. No, that's not true. There's a spectrum of writing. One end of it is for hostile audiences, the other end of it is for friendly audiences. And they aren't the audiences you think.
Yeah, we all "write every day." A lot of that is texts.
HOWS UR DAY
LAME WAN2 HOOK UP =)
Two people who know each other and who actually give a shit what each other says can communicate like this. It's a bare minimum. There's no poetry in it, it gets the job done. A sign that says "STOP" is a lot more efficient than a sign that says "You should wait here and look both ways so that small children are not crushed under your tires." But the former ain't prose.
There's writing where the audience needs your information. They want your information. They'll take it in whatever form they can get it, but the fastest, most efficient method is preferred. They may mock your grammar, they may mock your punctuation, but at the end of the day, they just need the information. This is a friendly audience and you can do no wrong.
Then there's writing where the audience does not need your information. In order for it to reach them it has to enchant its way in, exist on its own merits, communicate for communication's sake. This is prose, this is fiction, this is poetry, this is everything that anyone ever chooses to read for no reason other than they want to read.
And people want to read. Most people don't understand that.
I'm often in a position to mix television shows in which the contestants have been cut off from the world. They have no contact with news media, television, books, anything. Know what they do a lot of?
They read food labels. they read food labels to each other.
I don't think they know why. I don't think they realize that they're sitting there flirting with a girl and reciting the ingredients of a bottle of salad dressing to her. But they do. And that's because in the absence of any other writing, they'll teach each other to pronounce "riboflavin."
The trick, then, is to know if your audience is hostile or friendly to your writing. Like I said, it's a spectrum - and you have to know intuitively where they lie. Writing is, after all, communication, and the goal is to transfer an idea from me to you. How much florid prose does it need? How much vernacular? How much slang? How much artistry?
You're right. Backtracking only works while speaking. Li'l secret: speaking works better if you don't.
Know who you're talking to, know what they want, and give it to them. The rest of it is details.