Every unit is different. Every unit needs checking.

If you build in small batches or to order, no two units are quite alike. This is high-mix manufacturing: many variants, low volumes, and every build differs from the last.

That breaks the usual intelligent inspection approaches. A reference image can’t distinguish an acceptable difference from a real fault, and there aren’t enough samples to train a vision model. In a dense assembly, parts also hide behind other parts, so a fixed camera cannot see everything it needs to.

So the check falls back to people. Manual inspection is slow, varies between shifts, and it’s easy to miss a missing, misplaced, or wrong part.