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arXiv:2609.33738 ★ 77 Sep 27, 2026

Incremental requirements in creative writing: why a story built piece by piece comes out worse, even when every condition is met

Key result

The finding: the model can't rewrite already-finished text; it only stitches the new requirement onto what's already written, like a patch. Understanding this lets you gather all the story requirements into one brief instead of tossing them in as the conversation goes, and the story comes out noticeably more cohesive. The model can plan the whole plot, but only if it sees all the conditions at once, before generation starts. Drop a requirement in five messages later and it just sticks on top, with no connection to the rest of the text.

01

TL;DR

When you add requirements to a story as the conversation goes along (first the genre, five messages later a character, then you suddenly remember a special phrase that has to be in the text), the final story comes out structurally worse than if you'd given all the requirements at once in a single prompt. What's more, the model can formally tick off every item on your requirements list and the text will still fall apart on pacing, cause and effect, and setting up the payoff.

The thing is, the model can't go back and rewrite already-generated text in light of new information. It writes linearly and just "stitches" the new requirement onto what's already written, as if inserting a paragraph into a finished text rather than rebuilding the story from scratch. The spread across models is huge: one loses just 12% of quality under incremental delivery, another more than half.

The researchers introduced a metric called Creative Integrity, a joint score of "did it meet the requirements" + "did it produce a coherent story." With incremental delivery, models on average retain only 71% of the integrity they achieve with a full brief up front. And even when two versions of a story formally meet the requirements equally well, the version written "with the full brief as input" still comes out structurally more cohesive.

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02

Method Blueprint (what happens and what to do)

WHAT BREAKS QUALITY:
Requirement 1 → the model writes a chunk of text
Requirement 2 (3 messages later) → the model "stitches" it onto the finished text
Requirement 3 → another patch, not a rebuild
= the structure crumbles, even if every requirement is formally met

WHAT WORKS BETTER:
All requirements at once in one prompt → the model plans the whole story → higher coherence
OR, if requirements came up along the way:
Collect the accumulated list → ask for the whole text to be rewritten from scratch
03

Example

Task: You're writing a script for an ad sketch about a delivery startup for Reels/TikTok. You start a conversation with ChatGPT and remember details along the way: "let's have a meme about the courier," "and at the end, a twist that the customer used to be a courier himself."

How people usually do it (bad):

Prompt 1: Write a sketch about food delivery, 30 seconds, funny.
[the model writes]
Prompt 2: Add a joke about the courier always being late.
[the model adds the joke to the finished text]
Prompt 3: And make a twist at the end — the customer turns out to be a former courier.
[the model tacks the twist onto the end]

The result is a sketch where the lateness joke sticks out as a separate chunk and the twist isn't set up in advance: the viewer won't get why it's surprising and funny.

How to do it better:

Prompt (everything at once):

Write a script for an ad sketch about food delivery for Reels, 30 seconds.
It should be funny. Must include:
- a joke about the courier always being late
- a twist at the end: the customer turns out to be a former courier
Build the plot so the twist is set up in advance — 
the viewer should see the beginning in a new light once they learn the truth.

Or, if the requirements already came up during the conversation:

Here are all the requirements for the sketch I've given you in this conversation:
[list]
Rewrite the script from scratch, in full — don't edit the previous text,
create a new version where all these requirements are built in from the very start.

Result: The model plants "hooks" for the twist in advance and weaves the joke into the overall rhythm of the scene instead of inserting it as a standalone line. The final text comes out more cohesive: the reader or viewer won't feel the "seams" between the added pieces.

04

Why it works

The model generates text linearly, word by word, and when you add a requirement after part of the text is already written, it has no mechanism to "go back and rewrite everything with the new condition in mind"; it just slots the requirement into what's already there. That's the weakness: a local fix instead of global replanning.

The LLM's strength is that it's excellent at planning the whole story if it sees all the conditions at once before it starts writing. That's exactly why a complete brief up front works better: the model can think through the story arc in advance, set up the twists, and distribute the pacing.

Control lever: if you feel your task has piled up a lot of edits over the conversation, don't ask to "add one more thing"; collect the final list of requirements and ask for the text to be written from scratch. That's the only way to make the model replan instead of patch.

05

Limitations

⚠️ Only open-weight models were tested, not top closed models. It's unknown how strongly the effect shows up in the latest GPT-5/Claude/Gemini; they may hold structure better under incremental delivery.

⚠️ The effect is strong specifically in creative writing with 5–9 dialogue turns. For business texts, where only factual accuracy matters rather than narrative coherence, the degradation may be smaller or of a different nature.

⚠️ Automated evaluation doesn't always match human judgment, especially on originality: the automated judge thought incremental delivery even slightly improved originality, while human readers thought the opposite. Don't treat automated scores of creative text as absolute truth.

06

How it was studied

The team took 160 short-story assignments in six genres (fantasy, mystery, romance, science fiction, historical fiction, comedy) and made two versions of each: the full brief at once and the same brief split across 5–9 dialogue messages. They ran them through six open models, yielding 960 paired comparisons.

Quality was assessed with a checklist of met requirements and five text parameters (structure, writing craft, originality, genre fit, characters). Some of the scoring was done by an LLM judge and some by three human raters on 50 pairs, to check whether the automated scores matched human ones.

The most interesting part: even when they kept only the pairs where both versions met the requirements checklist equally well, the incremental version still turned out structurally weaker. This means that checking "were all items met" isn't enough: a story can formally pass every checkbox and still be worse assembled as a story. The spread between models (from 45% to 88% of quality retained) shows that resilience to incremental edits is a separate property of a model, not directly tied to its overall capability.

07

Resources

The Effects of Incremental Instruction Delivery on Language-Model Creative Writing — Anshuman Singh, Haseeb Yaqoob, Abrar Eyasir, John Manavalan. Dataset and code: github.com/solusops/SISTER-2026-Team19

Research digest

Key result

The finding: the model can't rewrite already-finished text; it only stitches the new requirement onto what's already written, like a patch. Understanding this lets you gather all the story requirements into one brief instead of tossing them in as the conversation goes, and the story comes out noticeably more cohesive. The model can plan the whole plot, but only if it sees all the conditions at once, before generation starts. Drop a requirement in five messages later and it just sticks on top, with no connection to the rest of the text.

Principle

The rule is simple: don't add requirements one at a time in the conversation; gather them all and give them at once. The model here is like a builder: hand it the full house blueprint and it'll lay the foundation for the future balcony in advance. Say "now add a balcony" when the walls are already up, and it'll just nail one onto the outside with no support. The gist: an LLM can do global plot planning only at the start; after that, all it can do is a local patch.

Why it works

The reason is technical: the model writes text strictly linearly, chunk by chunk, and physically can't go back and rewrite paragraphs it already output in light of new information. It slots the new requirement in as a separate insert instead of rebuilding the story from scratch. The spread between models is huge: one loses only 12% of cohesion under incremental delivery, another more than half. On average, models retain only 71% of the story cohesion they achieve with a full brief up front, and that's with formally identical fulfillment of all the requirements in both cases.

When to apply

Creative writing → scripts, stories, social media sketches where twists and cause-and-effect matter, especially when the conversation with the model stretches to 5-9 or more messages with edits. Not critical for business texts where only factual accuracy matters, not narrative cohesion.

Mini recipe

1. Assemble the whole brief: before the first prompt, jot down all the requirements: genre, characters, required phrases, the twist at the end. 2. If edits have already piled up: don't ask to "add one more detail"; collect the final list of everything discussed in the conversation. 3. Ask for a rebuild: tell the model explicitly: don't edit the previous text, create a whole new version that accounts for all the requirements. 4. Check for seams: reread the result; if a joke or detail sticks out as a separate chunk instead of being woven into the rhythm of the story, that's the sign of a patch, not a rebuild.

Examples

[BAD]: `Write a sketch about food delivery, 30 seconds, funny.` → then `Add a joke about the courier always being late` → then `And at the end add a twist — the customer is a former courier himself` [GOOD]: `Write a script for a sketch about food delivery for Reels, 30 seconds, funny. Must include: a joke about the courier always being late, a twist at the end — the customer turns out to be a former courier. Build the plot so the twist is set up in advance — the viewer should see the beginning in a new light.`

In plain words

Models write text linearly, word by word, and they completely lack a global replanning function. When you spoon-feed the brief (first the genre, then the hero, and on the fifth message you remember the hidden twist), the model doesn't rewrite the plot from scratch. It just sews the new wishes onto the already-generated frame, producing local patches instead of a cohesive story.

It's like building a house and, while the roof shingles are going on, telling the contractor: "Hey, let's dig a pool right in the living room." The foundation is poured, the walls are up, so the crew just jackhammers through the floor in the middle of the room. Technically your whim is granted, but nobody can live in this Frankenstein: the structure is cracking and the floor plan logic goes out the window.

The study shows that a single master prompt at the start crushes step-by-step add-on edits. To get decent pacing and working Chekhov's guns, you have to lay out all the constraints at once: genre, conflict, key phrase and final twist. The model has to see the whole map, or the text will fall apart even if the model formally accounts for every little item.

It was tested on short stories, but it's the same pitfall in any creative task: from Reels scripts and ads to sales landing pages. If you're drafting a sketch and mid-generation decide to throw in "let's make the courier turn out to be the startup's founder", you'll end up with mush. Any storytelling needs a foundation, not hastily bolted-on crutches mid-process.

Bottom line: stop having "heart-to-heart chats" with the model and handing over wishes after the fact. Gather all the inputs into one tight prompt, then hit Enter. One comprehensive brief beats ten edits along the way. Otherwise you'll get not a gripping script but a dull set of ticked boxes you'd be embarrassed to show anyone.

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Based on Incremental requirements in creative writing: why a story built piece by piece comes out worse, even when every condition is met arXiv:2609.33738

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