Overview
Custom nodes make ComfyUI much more capable, but each extension adds dependencies and another potential failure point. A node may install correctly while a required model is still absent.
Large assets can consume several gigabytes. The ControlNet Union model used here is approximately 2.5 GB. The InstantID IP-Adapter and ControlNet files add several more gigabytes.
Refresh and restart are not interchangeable. Refresh is needed to expose newly installed model files in dropdowns; a restart is needed to load newly installed custom nodes and dependencies.
An automatic missing-node installer simplifies imported workflows, but it cannot guarantee that every separately hosted model or manually placed asset is present.