There are calculations done on closeouts, such as powerplant panels, which shows the load is low. Indeed on the A380 Reverser, the panels don't have a closeout.
I'm assuming your talking of sections going from monolitihic to sandwich panels, and the closeout being the portion between?
In the closeout portion, it is more important to show that the core shear value is adequate to allow distribution to flow between inner and outer skins, to the monolithic part.