In systems with hundreds of atoms, including layered nanocomposite materials and protein-ligand complexes, the magnitude of the CP correction is much larger than it is in small benchmark dimers, which reflects the sizeextensivity of BSSE. Absent CP correction, double-ζ results for systems of this size may be 30-40 kcal/mol (or more) from the DFT/CBS limit and should be considered unreliable, which is notable given the prevalence of such calculations in the literature. On the other hand, CPcorrected interaction energies converge towards the CBS limit in a systematic manner, and they do so much more rapidly than the uncorrected results. CP correction again proves to be cost-effective despite the added expense of computing the monomer energies in a supramolecular basis set. We recommend CP-DFT/def2-ha-SVP as a robust and relatively low-cost approach to compute ∆E int in large systems.