Roll forwards and back should usually be done slowly and carefully.

However, during a major outage, there is a good reason to do the rollback very fast. Ie. Within 1 minute. Fast rollbacks end any outage sooner. And if your service is already down, you have nothing to lose and everything to gain.

That provides an interesting infrastructure problem. Fast rollbacks probably involve restarting a large number of servers, having a large number of cold caches, etc. You can find new bugs that only rear their heads during a fast rollback. Things like docker registries getting overloaded, kubernetes control plane being overloaded, other services becoming unhealthy due to a large influx of requests, etc.

The traditional approach is 'dont take risks, don't do a fast rollback'. But that can double or more the length of your downtime. Especially if you roll back the wrong thing first.

I'd therefore encourage preparing ahead of time for fast rollbacks. The dev/test environment should automatically do 'big bang' rollbacks every week. Production rollbacks should even be practiced from time to time, getting faster and faster each time, keeping an eye on metrics to look for instability.