Yield in image processing inspection

We often see a requirement specification that states something like "inspection yield 99.9%".
I assume that this is probably derived from the actual yield rate of the product at the time of shipment.
The issue here is how to handle "unclear OK/NG" items.
In the case of automatic inspections, the worst case scenario of "outflow of defective products" will occur if inspections are not carried out with the mindset of "punish anything that looks suspicious. Therefore, it is difficult to judge whether it is really better to have a high yield.
Even if only 50% of the defective products are obtained by the "low-yield inspection system that only allows absolutely good products to pass through," man-hours will be reduced if only the remaining 50% of the products are visually inspected. On the other hand, if a "high yield but loose inspection device" can produce 99.9% of good products? On the other hand, can quality assurance be achieved with a "high yield but loose inspection device" that can produce 99.9% good products?
What about from the "field" point of view?