KE, momentum,arrow diameter, arrow material, arrow tune, shot angles, location on the shoulder blade itself (it's not the same thickness througout),animal size,broadhead design,cutting diameter......am I missing anything?

There are too many variables involved to narrow down a "Shoot don't shoot" involving shoulder blades on animals.

There will be those that say they can shoot through, those that can't ,even those that say they shoot through BOTH shoulders??Which also begs the question if some even know enough about animal anatomy to determine exactlyt what was hit.
The far edge of the "paddle" is different than the bony ridge of the spine of the shoulder blade.
Too many factors to make direct comparisons without in depth forensic type stuff.

Bottom line:
Do what you are doing in planning for the worst, do your best to avoid that shot and hope that one or more of the above variables comes through for you if you find yourself in that situation.