The proportion of empirical holo and apo sites missed by the advanced platform was respectively 0.1% and 6.5% compared to 11.2% and 28.4% using the simplistic ligandability assessment approach. Each "incorrectly predicted" holo site missed by either of the simplistic and advanced approaches was subject to visual inspection for presence of a ligandable cavity occupied by a ligand in the holo protein. For the incorrectly predicted apo sites; using the 3D atomic coordinate file of the subjective apo protein structure, the apo site in apo-covPDBs was aligned to its holo site counterpart from the covPDB pool and was visually inspected for experimental truncations and presence of residues fully forming the cavity in the ligand-complexed covPDB counterpart.