Floorguy,

You are right that you do not walk directly on the material used to level, but the movement of the floating floor will move the material below.

If you have movement in a floating floor, what is the cause?? The shimming is there to make no movement. Where is your common sense??

If you have movement, you didn't shim it enough. Gravity is a blessed thing, and viabration, makes mass sink to the lowest level, thanks to gravity.

Floorguy,
Where is this Floor Preparation Standard written?

What manufacturer or Industry Association lists using sand, dirt or non-affixed shimms as method to level sub-floors?

Using Sand to level slabs was a common practice for about one or two years in Southern Louisiana.... I inspected the failures about two years after installation. That was back in 1997 to 1999, maybe earlier...

At one time, years and years ago, either Kahrs or Harris-Tarkett recommended using sand to fill in the low spots in a slab when floating in their longstrip floating floors. I thought that was very weird but did try it once. I needed to remember where the spots were so I didn't dislocate the sand when installing the floors. The spots were covered by the poly film and white foam underlayment and couldn't be seen well. After that experience, I started using cementious patching compounds as I felt they were simply easier/batter. I don't see HT or Kahrs recommending sand anymore.