It's actually longer than 5 minutes. There is the duration of the 2% canary deploy where we start to see pick up of traffic, a 5 minute wait, then a 20% "deploy", and a 5 minute wait. All in all this comes out to around 10-15ish minutes in canary. This is a stage where we can almost instantly shut off traffic to the canary deploy.

Could we reduce risk by lengthening the process? Maybe, but you also make deploys longer which means less stuff can get through in a day. This makes devs respond with larger PRs, for example, which increases the risk profile.

So we need to balance time and duration. Typically large problems will manifest quickly, or take a lot longer to detect (and thus are generally more minor problems) when you have our scale of a user base in my experience.