Screenwriting : Plotting away... by Carla Iacovetti

The plot is the road that drives you story from the beginning to the end. If you don't plan it accurately in advance you risk getting lost. On the other hand getting lost it's not necessarily bad cause only when you dare losing control and let things happen unconsciously you can cross new unexpected territories.

Good point, but when you have a lousy plot and no character development, you basically create a disaster. :)

Sure, but a lousy plot doesn't imply flat characters. On the contrary, when the story is not plot-driven you have to go in depth with your characters, since the story is driven by their conflicts and contradictions . Anyway I reckon that if you writing without planning you need a hard work to revise and polish everything you've done in order to give a sense to it.