I've always been the sort of person who focuses best with a deadline. I can sometimes set my own deadlines (I usually do pretty well at NaNoWriMo), but there's nothing like external accountability.
It used to take me months before I could pick up something I'd written and have any objectivity about it. I don't have that luxury now. Having external deadlines has made me a lot more brutal. If I have a vague suspicion that maybe something isn't quite working, I don't dither - I rewrite it, or I nuke it entirely.
On the other side of it, I find myself leaving parts I quite like, even if I'm not entirely sure why I think they work. There is no way there's ever enough time to rewrite to the point I'm 100% convinced it's all perfect, so I learn where to draw my lines.
Also: I no longer wait for the muse. The muse doesn't ever show up when you need it. (I don't mean our
muse, of course!) Sometimes you have to sit and write even when you're convinced it's garbage, because at least then you have garbage you can revise.
In some ways, writing is not as much fun as it used to be. In other ways, it's much more satisfying, because after all the madness I have something finished.