I have noticed an upward trajectory in the "closeness" between first draft and final draft (there is significant modification and tinkering in between), but with that general trend, there is variation around the line that makes each project unique, some requiring more work than others. I'd kick myself in the butt if I didn't see that upward trajectory, by the way, because it would mean I'm not learning from my mistakes, or gaining from my experience, or both.
I no longer give myself permission to write first-draft crap, although I'm not yet able to stop the gaseous emissions. I now give myself permission to fart through the first draft. I wonder if Uncle Jim has a certificate for that.