Are de-kitted lenses more prone to sample variation?

As I mentioned in another recent post, I've had the opportunity to visit their manufacturing facilities in Yamagata Japan. At the time the manufacturing line starts producing the final product, all the tweaking has been done, checked and rechecked numerous times. I had the opportunity to discuss quality with them, a topic that the Japanese companies take very seriously. The majority of the product variations can be attributed to shipping related matters which are often beyond their control. The packaging for every product undergoes some elaborate 7 point drop testing.  It was explained that today, with most lens using some sort of software correction, minor tweaks take place asn firmware updates if required. If you look closely, Panasonic has had relatively few updates suggesting they got it right the first time. One of the last updates Panasonic made was to increase the AF speed to 240 FPS - making a good product even better.

Pikme wrote:

No one has the kind of data needed to know the answer to your question.

But if I were speculating, I'd guess the highest risk of getting a bad lens comes from the first batch produced, before the manufacturer has had time to make any needed adjustments (human and/or mechanical) to the manufacturing process. So the question would be whether the kits get the first lenses or whether they are sold separately first, then later added to promotional kits. And that would depend on the specific lens and specific country of sale, as it really does vary.