At an awards get together once for a contest, I was approached by a writer whose script I thought was very good and a script that I thought should have made the finals, but didn't because other readers didn't agree with me. The author did make the list just before finals, which is a pretty good place to end up considering the number of entries. But he asked me if there was a reason he didn't make the top ten.
Usually there is a very definite reason, though one doesn't want to necessarily tell a person that. But often there really isn't a good, solid reason why. Often when a script gets so close to the top, but doesn't make it, it's almost impossible to say why. And that's what I told him. That at that point there really was no reason one could give for it happening. For his script, there were all sorts of factors (some of which I didn't know or understand) that happened to happen to stop him from crossing that last barrier.
In relation to this, I've been asked before whether someone should reenter the same contest. It actually happens a lot, authors reentering their scripts. Probably for three reasons, the first being that they don't keep good records and forgot that they already entered the contest with this particular script the previous year. A second is that they hope that this time around they'll be read by a different reader or sets of readers who might like the script better and thereby make it further than before.
The third reason is that they have substantially rewritten the script. This is actually the only good reason for reentering the same script in a contest. And I've known scripts that have done better because of it.
But when it comes to entering the exact same script hoping to do better, I suggest it's not a wise idea. True, if one didn't even make the lowest group of say, quarter finalists (or whatever they call the first cut), then it is possible you might do a bit better if one gets a different reader. But beyond that, it's unlikely the script will go any farther, if for no other reason than the script will hit the same reader or readers as before (contests tend to use many of the same readers year after year) and they will recognize the script and will probably have the same reaction to it.
In addition, if one made the next to last cut, yes, it is possible that another go round just might get you into that top ten. But what I told the person is that the likelihood of the stars being in a slightly different alignment that year is so unlikely that the person should reconsider spending the enormous amount of money (and screenplay competitions are expensive) to enter. It would make much more sense to just enter a different contest.