Strategic policy planning has gained increasing importance in international energy and climate policy. This paper aims to contribute to the debate on stringent policy planning by drawing lessons learned from two decades of strategy development in the field of European energy efficiency policy. Since the inception of the first national energy efficiency action plans under the Energy Services Directive (2006/32/EC), the European Commission and the Member States have had a long experience in planning national strategies. This paper analyses the lessons learned in setting up national energy efficiency strategies and traces the progress made in 2007-2020. Our findings show that major improvements are attained in the latest national energy and climate plans through the adoption of harmonised reporting approaches, evidence-based target setting methods, establishment of better monitoring systems and broader consideration of policy packages. Various areas with a significant potential for further improvements are also identified, ranging from more coherent reporting framework for policies and measures to the need of setting up systems that encourage the adoption of targets in line with a country's cost-effective energy efficiency potential. Embedding energy efficiency in the larger climate policy framework, considering how it can support pressing socioeconomic challenges, is also of pivotal importance.