Comment by anonymouskimmer

> However, if you inspect a small number of products at random, you'll detect a large percentage of the quality issues.

As quality issues become fewer, the odds increase that inspecting a small number of products at random will lead to you thinking that there are zero quality issues. Have your inspections procedure scale and adapt to the relative proportion of quality issues you have reason to believe exist. And if you believe you truly have zero quality issues, then you need to switch to an immediate feedback procedure (such as an anonymous tip line, or a non-anonymous one for customer feedback).