An interesting thread indeed.
I remember launching right into my first novel when I was 16, hand-written, about 300 pages, and utterly godawful. I had no idea of where it was going, but the enthusiasm just compelled me to churn out word after word, suffice to say I learnt my mistake.
So I started on short stories, problem was I could barely write a short story under 40 pages, after a few I saw this as a sign I should return to novel writing anew. I made a planned outline, started writing - 200 pages, it fell apart.
Third novel now, same thing.
Fourth novel ( couldn't make this up, could you?
), and one which I feel is by far my best work, it has a theme I care about and a very personal style to it. So far I've written about 80 pages on it, but I find myself going in fits and starts, I tried the 'write something every day, no matter what' but ended up producing such utter trash it started affecting my morale. So now I write in fits and starts, its a habit I'm trying to break, I know there's some measure of talent in there but it seems impossible to channel it into a regular routine - when I write, I write very well, otherwise I just don't write at all.
You really do need to try to 'tame' your output, as has been suggested try to write a certain number of words a day and once you are achieving that with ease then increase the output, I failed but my muse is covered in pig grease and utterly invisible; I very rarely lay my hands on them.
Plus, here's an important point, so important I'm going to give it some obnoxious caps; NO-ONE HAS TO READ WHAT YOU'VE WRITTEN UNLESS YOU LET THEM, we all feel that 'fear' about our work but the truth is someone isn't going to break into your house with the sole intention of chuckling at your ill-formed characters or dialogue as they stand. So, crucially, don't be afraid to write and play around, get your hands dirty, have fun. THEN you can polish it up and snip all the loose ends before you show it to anyone, but before that point what you can do is almost limitless, dive right into it and start making a mess, a mess signifies life, humour, involvement, and those qualities will be open to you if you're honest enough to put down what you think and feel.