Answer
Common patterns separate application source code from deployment config (config/manifests in their own repos), and often split per-environment or per-team. Monorepo vs multi-repo trade-offs balance simplicity against blast radius and access control. Kustomize overlays or Helm values manage environment differences from a shared base, and the App of Apps or ApplicationSets manage many apps.
Real-world example Source code lives in app repos while a central 'gitops' repo holds environment overlays that ArgoCD watches per cluster.