I've a feeling that it shows, but/and it depends on the theme very much.
// A long-winded "because I'm bored and don't want to work" ramble follows:
Say, I make a one-weekend "The Third Way To Spellhold: Cowled Wizards Love You!" mod (Is it doable? Sure), and I decide to present it as my Iron Modder X entry. The hour comes, and the Overlord announces the topic. Will my mod fit?
Let's take nine previous themes:
"Being the Bhaalspawn Means Never Saying You're Sorry" - easy as pie. PC kills his/her Cowled Wizard superior in the end, and the topic is a-a-aall over it.
"Careless Words Cost Lives" - same thing.
"Blaze of Glory" - add a nice presentation "You're Among the Cowled Wizards Now" ceremony, and the game's in the bag.
"A Hero For All the Wrong Reasons" - sure, because only an idiot would go to Spellhold to face one of the greatest wizards on Faerun on that wizard's terms.
"The Price Of Friendship" - again, going to Spellhold means saving dear little Imoen; still on-topic.
"A Broken Promise" - because the Cowled Wizards are renown for breaking their word(or will be, after the mod is released);
"A Kiss Before Dying" - a romantic interest says a few words, and we're all done(though Idobek's IM contribution kind of warns against it).
But take "Some of My Best Friends Are Slimes" and "The Last Mug of Ale In Amn." - and you're hard pressed to fit pre-made content into it. In fact, it's easier to start from scratch.
... see what I mean?