I read or heard somewhere that Tolkien, when he was writing the Lord of the Rings (which he, not surprisingly approached as a singular book, rather than three) he would start writing until he got stuck on something. And then, he would take it out and start again from the beginning. The end result being, by the time he got to the end: it was really done.
I'm not sure how true this is, and I'm pretty sure that this isn't exactly a "recommended" method of writing, but I think there's something meritous about this kind of approach, possibly on the shorter end of the spectrum.
After all, most short stories are, well rather short, and from my experience, sometimes starting a-fresh might be more time-economical than trying to salvage some husk of your original work. It might also solve the problem of wooden characters in the first third of your piece (because it usually takes people too long to really get to know and expect characters.)
I also know that this sort of "fresh start" mentality should of course be balanced with a strong impulse to finish things, and I think this is where my own short fiction gets tied up. I have three-four short fiction pieces lying around, and none of them have good endings. Or really any endings. It's important to finish things, and so maybe the "start over if you get stuck" method would only serve to complicate this.
We should also mention that Tolkien had a tenured position at Oxford, he was in a position where success as a fiction writer didn't (and really couldn't) have been confused with prolific-ness.
Onward and Upward!