How much do you day-dream before starting your writing process?  How important is thinking before writing?

After years of thinking about it, and writing a different version of it, Sylvester Stallone famously pounded out the script for Rocky in just 3 days (although it went through several comprehensive rewrites before it was purchased by Irwin Winkler and Robert Chartoff).  John Hughes wrote The Breakfast Club in a weekend.  What was their secret to writing such excellent screenplays so quickly?

"The more circumspectly you delay writing down an idea, the more maturely developed it will be on surrendering itself,” said Walter Benjamin in his Writer's Technique in 13 Theses.

Is there value in powering through a quick first draft before launching into the development process?