I'm a proponent of doing whatever it is you want to do well. How to get to Carnegie Hall...ba dump bump.
It's true. Genius and talent and all that are great, but practice is better. The more you write, the better the quality, with one caveat. Mindless writing will never improve.
I talk to people all the time who tell me how much they write, and they often sound boastful when they say, "I've got notebooks full of stories." One man told me he'd written 75 short stories in the past three months. "Good," I say. "But might some of them need editing?" His face told me what he didn't want to say aloud. It's more fun to keep writing the New Idea than it is to perfect what's already written.
Part of the work of writing is rewriting. What you've captured on file or paper must be examined with a critical eye, must be fine-tuned with the reader in mind. You write for yourself, of course, but someone else has to understand your work or it becomes merely a journal. The work of being a writer is making what you say accessible and appealing to others.
So write as much as you like; it's good practice. But if you want to be published someday, I suggest you practice editing, too.