In college I worked as an inspector at a plant that made aerospace boards. Each board was tested multiple times, there were inspectors after almost every step,

In college I worked as an inspector at a plant that made aerospace boards. Each board was tested multiple times, there were inspectors after almost every step, to the point that each board was inspected at least 4 times during assembly, and then 2 separate full tests were done on every board. No sampling, each and every board was tested. Speaking to the engineers, our projected defect rate was <1%, and we achieved that. However, for rough numbers, this 1.6K board would likely cost >10K to achieve that level of reliability.