[DanBC]

> Because more eyes catch more bugs.

But for product inspection we have pretty good evidence, from millions of human hours of factory work, that it's a bit more complicated.

X makes a widget, and sends it for inspection by Y and Z. Y has a look, but assumes Z will catch anything that Y misses. But Z also assumes that Y will catch anything that Z misses.

You end up with two people doing a superficial inspection and missing problems.

Of course, that's only if they're doing the same inspection twice. If they have different and clearly defined inspection roles the two inspector problem doesn't apply.