NAND flash memory has become the dominant non-volatile storage technology across the computing spectrum, from mobile devices to hyperscale data centres. However, progressive cell degradation through program/erase cycling, charge trapping, and retention loss limits device lifetime and data integrity. This paper presents a comprehensive review of NAND flash wear mechanisms, classical and adaptive wear-management techniques-including wear levelling, error correction codes, and dynamic data migration-and emerging approaches for three-dimensional (3D) NAND. We introduce the Smart Score System, a transparent multi-metric composite health-scoring framework that integrates four complementary wear indicators: P/E cycle count, ECC error rate, access latency, and block temperature. A workload-aware dynamic weighting strategy adapts scoring priorities to operational conditions, while a predictive migration protocol pre-emptively relocates data from degrading blocks. We identify five key research gaps in the existing literature-limited multi-metric integration, absence of workload-aware adaptation, predominantly reactive operation, accuracy-interpretability trade-offs, and insufficient statistical validation-and demonstrate how the Smart Score System addresses each. The framework is designed for transparent firmware deployment and is shown to complement device-physics-aware approaches such as dynamic program/erase scaling (DPES) and real-time erase optimization (REO). The proposed approach provides a principled foundation for future flash management research targeting reliability, sustainability, and data integrity.