NAND Flash memories have gained tremendous attention owing to the increasing demand for storage capacity. This implies that NAND cells need to scale continuously to maintain the pace of technological evolution. Even though NAND Flash memory technology has evolved from a traditional 2D concept toward a 3D structure, the traditional reliability problems related to the tunnel oxide continue to persist. In this paper, we review several recent techniques for separating the effects of the oxide charge and tunneling current flow on the endurance characteristics, particularly the transconductance reduction (∆Gm,max ) statistics. A detailed analysis allows us to obtain a model based on physical measurements that captures the main features of various endurance testing procedures. The investigated phenomena and results could be useful for the development of both conventional and emerging NAND Flash memories.