The "And Then" Problem - as explained by South Park's creators.

South Park creators Trey Parker and Matt Stone recently crashed an NYU Film class on its first day and imparted some wisdom to the students that is simple, but essential when crafting a story.  I'll let Trey Parker explain  (around the 4:00 mark).  In the event the embed doesn't work for you, go here:

"We found out this really simple rule... we can take... the beats of your outline, and if the words "and then' belong between those beats, you're f**ked, basically.  You've got something pretty boring.  What should happen between every beat you've written down is the word 'therefore' or 'but.'  

"So you come up with an idea and it's like 'this happens... and then, this happens.'  No, no, no!  It should be 'this happens... and therefore, this happens.'  [or] 'this happens... but this happens.'"

In transcript form, that probably reads more confusing than it plays.  I recognized this advice immediately, though, because it's something I term the "And Then Problem" when writing up coverage.  As most of you know, writing up coverage usually involves producing a story synopsis.  Nothing makes you aware of the weaknesses in story construction more than trying to boil down 120 pages to a page and a half or two pages of description that covers all the important moments while still flowing effectively.

A well-constructed script often makes for an easily written synopsis because there's that domino effect that Trey is essentially describing.  One scene clearly connects to the next and has an impact. Bad scripts jump all over the place before settling on a direction - or they pick a direction only to sputter and allow intermediate beats to drop the ball.

If it helps, describe your script to someone and see how often you find yourself resorting to "And Then" in your descriptions.