If I'm on a deadline, I can produce 13,000 words of copy in a day. If I'm very lucky I might be able to produce 3,000 words of fiction in a day and most days I count 1,000 words of fiction as good. For what it's worth, I produce fairly clean prose so I can focus most of my revision on story factors rather than polishing words, which cuts down on that effort.

The key is finding a process that works for you and understanding that as long as you get the work done it doesn't matter what that process is. You can overwrite, underwrite, write a messy first pass and revise like crazy afterwards, or polish each sentence as you write. It really doesn't matter so long as the process works for you.