This is something of an elementary lesson, but a random check of the slush pile shows that plenty of aspiring scribes would benefit from having this rule spelled out for them - your first ten pages often decide the fate of your whole script. If your first ten pages suck, then I decide your script sucks and I decide that you as a writer suck.
If I'm lucky, I'll come across your terrible script during a time when I've specifically sent to thin out the slush pile. Let's say agency submissions are at a high and someone is merely needed to do a cursory glance at the slush pile and make sure nothing good is being overlooked. In a case like this, I might get to read your first ten pages, decide you have no talent at all, and then toss the script guilt-free into the waste bin.
If I'm unlucky, some slimeball manager managed to call in a favor and sent in your script as an official submission. More than likely this means that some development VP is going to have to get on the phone and sound knowledgeable as he passes on it. That means I get stuck writing the coverage, which as you know, ensures I have to read the whole thing.
At this point Mr. Lazy Screenwriter is probably breathing a sigh of relief, secure in the knowledge that even though his 92-page script takes 35 pages to hit its stride, the reader is going to have to read all of it no matter what, so the slow patch at the beginning is nothing to be concerned about. Indeed, in the bowels of every screenwriting discussion board, when the matter of the first ten pages is raised, there's always some belligerent bottom feeder to say "This talk of writing to impress the reader in the first ten pages is just paranoid bullshit. They HAVE to read the whole script! It's their job! You don't have to worry about this at all!"
Wrong. Because as we already discussed, I already decided you were a hack back on p. 10. And ever misstep you make after that - and I have NEVER seen a script with terrible first pages that miraculously turned into an awesome spec later - only reinforces what I've already decided about you. Think of me like your mother - I only see what you're doing wrong.
To overcome that negativity, the script would need a truly awesome concept, solid characters and great pacing and plotting. A writer good enough to pull that off is also usually good enough to make sure his first ten pages aren't garbage.
Ergo, if your first ten pages suck, you suck as a writer.
"Screw you!" says Lazy Screenwriter. "How the fuck can you tell anything by the first ten pages of a 120 page script! You should have to read the whole thing!"
Okay Champ, let's think of it this way. It's a lazy weeknight and all your favorite shows are in reruns. Your DVR accidentally deleted that Gossip Girl marathon you were saving for when your roommate went out of town and because Netflix has decided to throttle you, you've got two full days before you get a new DVD. The internet is down because Time Warner sucks (Heh, THAT'll surely send a lot of Google searches to my page), so you can't even waste time on Facebook. You could read a book, but you're determined to just veg and eat junk food.
So you go looking for a movie that you haven't seen on cable. Lo and behold, one is starting right as you hit Showtime. You don't recognize the title and the TV Guide description is vague. Therefore, the only way you can figure out if its any good is by actually watching it.
How long do you give the movie before you decide it's not something you're interested in?
Anyone who said more than ten minutes is a liar. Frankly, I think most people would give the movie less than five.
But Lazy Screenwriter, how can you make any call about if the movie is right for you if you don't watch the whole thing?
The first ten minutes - effectively the first ten pages - can tell you a hell of a lot about the movie. You know who the main characters are, what the genre is, and probably get some decent foreshadowing of the central conflict. What's more, they give the audience a reason to keep watching.
Forget this at your own peril.