Continuous delivery is becoming a standard, if you implement the right process you get a predictable deployment. When a change is made in the code, most of the time the build, test, deploy and monitor steps are followed. This is the base for anyone willing to apply automation to their release process.
If a failure is detected during the monitoring phase, then an operator has to verify and rollback the failing release to the previous known working state. This process is time consuming and not always truthful since it requires someone to keep an eye on the monitoring dashboard and react to it.
If the team is well structured and applies the devops way of working, then there will be someone on duty who receives an alert when something goes wrong. Alerts are triggered based on metrics, but still, after receiving the alert, the person on duty has to turn on their laptop (if not on-site), take a look at the graph, think for a moment, realise that the issue is coming from the last release and decide whether or not there is a need to roll back.
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