I was about to say there is no need to start a new thread, but I see you already have.
You have presented a data tree with 200 branches, each with six faces of a “voxel” (200 * 6 = 1200 faces total):
Voxels03_2024Nov4d.gh (386.9 KB)
If you apply Shift List it becomes five branches (40 voxels per branch, 5 rows of 8 voxels per row, or 40 * 6 = 240 faces per branch - 5 branches * 240 = 1200 faces total):
It’s great to understand data trees 
Many ways to manipulate them.
In this case, adjacent faces are effectively duplicate faces (if I understand your goal?) and there must be a way to ignore duplicates and get six branches of surface faces (left, right, top, bottom, front and back).
Have fun.