Law 19 · Scope & Design
Decompose Before You Scale
When it's unreliable, split it. Don't supersize it.
The principle
When output is inconsistent, the instinct is to throw more at the same shape: a bigger model, a longer context, more tokens. That rarely fixes a structural problem. It just spreads attention thinner. Splitting the task into focused, single-purpose passes almost always beats trying to make one overloaded pass smarter.
Why it happens
A single overloaded pass splits attention across too many goals. A bigger model or longer prompt may help, but it often leaves the structure broken. Decomposition gives each step one job: extract per item, classify per case, then reconcile across items in a separate pass. Least-to-most and decomposed prompting show why this helps: solve simpler sub-problems first, then feed their results forward. The gain is not elegance. It is inspectability. Focused stages can be tested, tuned, and repaired one at a time.
Watch for
- A single pass handling many items is inconsistent, and a bigger model or longer prompt makes it blurrier, not sharper.
- One call is responsible for several distinct sub-tasks at once.
- Errors cluster on the hardest sub-step that is buried inside an overloaded prompt.
In practice
Your invoice extractor is inconsistent across 30-line documents, so you reach for a bigger model and a longer prompt, and it gets blurrier, not sharper, because one overloaded pass is splitting attention across every row. The instinct to supersize masks a structural problem. Split it instead: extract each line item in a focused per-item pass, then run a separate reconciliation pass to total and cross-check. Several stages that each do one thing well beat one heroic pass trying to do everything.
Apply it
- Split the work into stages that each do one thing, like extract per item, then reconcile across items.
- Solve simpler sub-problems first and feed their results into later steps rather than answering all at once.
- Optimize and inspect each focused pass in isolation instead of supersizing one overloaded call.
The takeaway
Break the work into stages that each do one thing well. Analyze per item, then reconcile across items. A focused pass beats a heroic one trying to do everything at once.