Think of the canary as the last line of defense, not the first. You always aspire to deploy zero bugs into production, through good testing and other QA. But if

Think of the canary as the last line of defense, not the first. You always aspire to deploy zero bugs into production, through good testing and other QA. But if a problem happens, you want to limit the impact as much as possible. Affecting one site isn't great, but there is enough redundancy that overall service should be unaffected.