There is nothing more futile than a writer who tries to perfect one screenplay over a lifetime. Because the reality is this: nothing is perfect. Not even close. And here's another thing: the movie business is slow. Projects get tossed around for five, ten, sometimes twenty years before they get the green light. And even then, the chances of a film getting derailed are high.
Think of the worst movie you've ever seen in your life. I mean, something that is really, really, really bad. And now take a minute to be amazed – not because a bad film has been made. Be amazed that any film (good or bad) is produced. Just getting a movie to the box office is an achievement in of itself. Filmmaking is such a collaborative medium with so many people involved and so many ways for a film to fall apart, that the chances of success are microscopic.
The reality is that failure goes hand in hand with film. But failure is not unique to just Hollywood. Corporations, government, and every professional sports team in America are all defined by failure. How many new prototypes are rejected before a company scores with that next great product? How many bills die before one is finally passed on Capital Hill? And what about a .300 batting average? Striking out 7 out of 10 times is actually considered good.
And movie making is no different. Most movies never even make it out of the starting gates, and the majority that do actually lose money at the box office. This is exactly why you can't put all your eggs in one basket. You absolutely cannot be a writer who covets one singular idea, because if you are, you're setting your own death trap.
Have lots of ideas. Lots of them! And make sure they are fresh, original, unique - because a plethora of great ideas is truly your ace in the hole. As soon as you finish writing one script, immediately begin another. Always be creating something new.
Imagine: If you write one script a year, in a decade (and it does take that long to have overnight success), you've got ten finished screenplays, and the increased chances of achieving success with ten spec scripts versus one is obvious. Fresh and original ideas truly are the lifeline of Hollywood.