A racecar driver doesn’t mess around; he can’t afford to go back and perfect every turn. Nobody cares about second place.
I don’t mean to imply that writing a first draft is a race exactly, but it should be completed fast. The inherent problem for many writers – especially beginning ones – is that they want to make that first act flawless. It’s important to have a great first 30 pages, but if you spend a tremendous ammount of time revising, sculpting, and perfecting it, you are wasting the clock.
Why the Formula-1 pace? Simple. No one should give you feedback until it’s done. Once someone can look at the whole picture, the main note might be to change the dramatic premise in the first act, or maybe the second act reveals that the story is really about another character and not the current protagonist, ultimately meaning that it’s time to throw out the first act - maybe a page one rewrite - and start again.
You’ll have time to dress the cake later, but when it comes to first drafts… JUST GET IT DONE! Writing is rewriting! There will be many more drafts to come.