Continuous Integration (CI) practices have become central to open-source software (OSS) development, yet the relationship between branching strategies, merge habits, and CI performance remains underexplored. Understanding their role is crucial for explaining the variation in CI outcomes and for refining development practices. We empirically examine how branching models (feature-based vs.\ trunk-based) and merge characteristics (size and frequency) affect key performance indicators (KPIs).

Using a dataset of 565 GitHub repositories, we analyze both short-term trends and long-term evolution of development strategies. We find that while feature branching is strongly associated with higher delivery frequency and lower defect counts, trunk-based workflows (though rare) sometimes outperform in lead time and recovery. Similarly, frequent merges correlate with faster delivery and shorter lead times, regardless of size. A longitudinal subset reveals that projects shift toward feature-based development over time, but do not consistently adopt smaller or more frequent merges.

We also highlight methodological limitations in mining GitHub. Future research should incorporate longitudinal repository tracking and developer surveys to capture workflows that are invisible to snapshot-based analysis. This study contributes to a nuanced understanding of how code management practices shape CI outcomes in collaborative OSS projects.