Anybody have any experience or thoughts on their engineered products

Ive installed a lot of Hallmark. Not lately though.
What really bugs me lately about many engineered is it seems none of them are kerfing the backside. And that creates stress in the plys which makes planks bow and twist and pull out of adhesive a n d also makes floaters bouncy.
Its a cheap shot to the installers by taking the kerfing off the line just to save a buck.
Kerfing should be mandatory but good luck cus the industry and doesn't give a shit.

Stephen:

I mentioned that to my milling operations years back. However, they did have kerf cuts every six inches. I felt it needed more. Works fine to this day providing the subfloor is flat to 3/16" over a span of ten feet.

Dips and high spots don't count

Seems cuts every six inches is standard. Might have seen four inches.
That flatness standard comes from the concrete industry and really has nothing to do with wood flooring or any type of floating floor.
That's the flatness standard concrete finishers are supposed to get the slab. And subsequently adopted by the floor covering industry. No one knows why!
I think slabs should be dang near flat as possible or you get voids under glued hardwood with 3/16's.

Case in point, these LVP manufacturers can some times have more stringent flatness guidelines in their literature because they know too much vertical movement can break the cheesy locking mechanisms, and they are small and brittle.

I just recently learned about the kerfing on the backside of the engineered flooring watching one of Ken's videos.

Could anyone elaborate more on it, what it's used for, it's importance etc.?

Thank you.