So fiberglass batts 12" thickness. The goal is to not let the insulation become compacted or have gaps between unconditioned and the conditioned space.
When a drywall nailer is fastened to the top plate of a wall that means if projects into the attic space. The fiberglass forms an arch over the protrusion.
Is the most preferred method to slit the kraft paper and hollow out fiberglass so it sets flush with the future ceiling plane? Is there a gain doing this...assuming the insulation would otherwise just have a crown in the attic meaning still the same thickness?