Detect errors at the earliest catchable point — correction…

Place error detection checkpoints at the earliest point in a process where the error can first be caught, because correction cost increases exponentially with propagation distance downstream.

When This Fires

When designing error detection architecture for any multi-step process
When deciding where to place quality gates, reviews, or validation checks
When errors are consistently caught late and correction costs are high
Complements When the cost of late error discovery exceeds 5x early… (phase-gate cost ratios) and Place pre-flight checks at the prep/execution boundary… (pre-flight positioning) with the general placement principle

Common Failure Mode

Placing all checkpoints at the end: "We'll review everything before shipping." End-of-process review catches errors but only after maximum propagation. An error introduced at step 2, caught at step 10, requires rework of 8 steps. The same error caught at step 3 requires rework of 1 step. End-of-process review is the most expensive possible detection architecture.

The Protocol

(1) Map your process: what does each step produce, and what errors can first be detected at each step? (2) For each error type: identify the earliest step where this error becomes detectable. Place a checkpoint there. (3) The checkpoint doesn't need to be comprehensive — a quick validation that catches the most common upstream errors is sufficient (Checklists are 5-10 items that catch what competent people…). (4) Multiple small checkpoints distributed early in the process outperform a single comprehensive checkpoint at the end. Each early checkpoint reduces the propagation distance for its error category. (5) Track where errors are actually caught: if most errors are caught at late checkpoints, you're missing opportunities for earlier detection. Can those error types be detected sooner?