Abstract: Complex driving environments are created by mandatory lane merging in work zones, which often lead to congestion and traffic conflicts. To address this issue, numerous studies have examined the effectiveness of various merging strategies, with Early Merge and Late Merge being the most commonly assessed. While some researchers have compared these strategies under similar conditions, many studies evaluate individual strategies across diverse traffic environments, resulting in limited consensus on their relative performance. These individual findings are often used as base models for developing cooperative and more advanced lane merging strategies. This paper presents a comprehensive literature review of existing merging strategies and their influencing factors, along with a meta-analysis comparing Early Merge and Late Merge against the conventional approach. A total of 53 studies were reviewed through the systematic review. The meta-analysis revealed that the lack of consensus in the literature stems from substantial heterogeneity, indicating that models derived from single studies may be unreliable. Traffic volume and heavy-vehicle proportion emerged as key factors shaping strategy efficiency. Reducing heterogeneity in future research will require evaluating each strategy across a wider range of work zone layouts, traffic volumes, and vehicle compositions. The findings of this study help clarify current evidence, guide future research, and support the development of more effective merging strategies for future work zones.