I toss chapters, I toss sub plots, I toss characters... but do not think I have ever "burned down" a story like you suggest.
I do not use an out line, I fall in with the camp that says "sit down, and write." I explore my way through story writing. Which means I probably have more tossed chapters then an out liner... but its the way I am wired to work.
For example I am currently writing book four in my series. I have about 30-35k written... but I plan to cut out an entire sub plot because it is to big. I will set it aside and turn it into book five. That will cut me back probably to 15-17k words and remove 2 major characters from the book. So I guess that is like burning down?