Trunk-Based Development at Scale: Empirical Analysis of Branching Strategy Impact on Integration Frequency, Merge Conflict Rate, and Delivery Performance
Branching strategy is a foundational DevOps decision that determines the cadence of integration, the severity of merge conflicts, and the attainability of continuous integration as defined by its original proponents. Despite the strong advocacy in practitioner literature for trunk-based development (TBD) over long-lived branch strategies such as GitFlow, rigorous empirical evidence comparing their delivery performance consequences has been limited. This paper addresses this gap through a large-scale empirical study of 30 engineering organizations across six industries, combining pipeline telemetry analysis with practitioner surveys (n=529) and structured interviews. We operationalize six delivery performance metrics for comparison: integration frequency, merge conflict rate, build failure rate, time to green build, deployment frequency, and change failure rate. Organizations practicing TBD with feature flags exhibit statistically significantly higher integration frequency (mean 14.2 integrations per developer per week vs 1.8 for GitFlow), lower merge conflict rates (0.12 vs 0.89 conflicts per pull request), and 48% higher deployment frequency. Subgroup analysis reveals that TBD benefits are amplified in teams larger than 8 engineers and in systems with more than 40 microservices. We also identify four TBD adoption prerequisites — feature flag infrastructure, fast build pipelines, comprehensive automated test suites, and code review tooling maturity — and provide a readiness assessment instrument.