Depending on my mood, and the subject at hand, YES.
Sometimes I am writing for a specific purpose or goal. In those cases writing may or may not be cathartic for me. Other times, when I find myself in a bad place, then writing is very cathartic for me. At those times, I will write and write and write and never intend it to be seen by anyone.
Nobody else knows what I'm going through when I write like that, but it still seems to help a lot, because I can say whatever I want to whomever I please, in any way I desire. The ability to take those liberties, which are not appropriate in the real world, is incredibly cathartic.