Manual backups fail. People forget. Automated systems don't.
Popular tools: Oxidized (open source, stores in Git), RANCID (older but stable), SolarWinds NCM (commercial, GUI-driven), and Ansible (config deployment and backup via playbooks).
Oxidized workflow:
Connects to each device on schedule
Retrieves running config
Compares to previous backup
If changed, commits to Git repository
Sends notification of changes
Git integration gives you version history and diff views. When troubleshooting, you can ask: "What changed in the last hours?" and get a precise answer.