Health Benefit Package design and revision are central to the realization of universal health coverage in low and middle income countries. The increasing complexity of health systems, rapid innovation in health technologies, and the limited fiscal space available to public payers require decision making approaches that are both analytically rigorous and operationally feasible. Over the past decade, health technology assessment and economic evaluation have become institutionalized in many national priority setting processes, yet the time intensive and resource demanding nature of traditional evidence synthesis has created persistent misalignment between the pace of policy making and the speed at which reliable evidence can be generated. This study develops a comprehensive conceptual and methodological framework for integrating adaptive evidence synthesis and economic evaluation into Health Benefit Package updating processes, drawing exclusively on internationally recognized standards and empirical analyses contained in the provided reference corpus. By synthesizing the Ethiopian experience of Health Benefit Package revision, global surveys of health technology assessment practice, methodological advances in rapid and adaptive reviews, and empirical studies on the timeliness and durability of systematic reviews and economic models, this article demonstrates that adaptive methods are not merely pragmatic compromises but are epistemologically coherent and policy relevant approaches to evidence informed priority setting. The methodology combines institutional analysis, comparative review of rapid evidence services, and critical appraisal of adaptive economic evaluation techniques. Results indicate that when appropriately structured and transparently reported, adaptive methods can preserve scientific rigor while significantly improving the timeliness and relevance of evidence used in benefit package decisions. The discussion explores the implications for governance, methodological standardization, and long term sustainability of Health Benefit Package updating in low and middle income countries. The article concludes that adaptive evidence ecosystems are essential for ensuring that Health Benefit Packages remain responsive to changing population needs, technological innovation, and fiscal realities, thereby strengthening the credibility and impact of health technology assessment in the pursuit of universal health coverage.