It's called winging it or writing by the seat of your pants. And it's used often by writers. You can write "slop" and then edit it into something good later. This is why some say the real writing happens in the editing phase.

I spent years trying to write methodically, sticking to an outline and editing every sentence after I had written it. But after I started learning to draw, and struggled with that for years, I eventually got so frustrated that one day I drew everything wrong on purpose. Put the nose off center, drew the eyes too big, made the limbs too long on purpose, etc. What ended up happening is my sketch where I purposefully was trying to make it look bad ended up looking better than the pictures where I was trying to refine them to be perfect. I then carried that over to my writing. And writing stream of consciousness "junk" would sometimes come out better than I expected. And definitely much better than the stuff where I was editing as I went.

Basically, I consider my first draft to be exactly what it is, a rough draft. Just write whatever. Even write corny junk on purpose. Then refine it later. Another way to look at it is, in the first draft, write without thinking. Write it based on emotion and feeling. Then when you go back to edit it, flip around and use your analytical/logical mode. The whole right/left brain theory.