That's to be expected, in this test setup wall density is the only thing that matters (and Blender physics friction model is probably not quite realistic either). But heavy rolling ball impact isn't the kind load these walls are normally subject to.

Seems a lot of work for an intuitive result. If a wall uses only 50% of the material per linear foot and is less than 200% length, well duh it's going to save bricks.

Though depending on the wall the precise savings may be different, in a flemmish bond some bricks are laid header out (spanning the two bricks) where it looks like the model is just 2 offset walls side by side

I also think the strength test is missing the point. any focused damage is likely to be more severe on a thinner wall, period. But I believe you can make a crinkle wall of relatively arbitrary length with decent height whereas an buttressed straight wall of sufficient length might be something you could practically push over with your hands.