[DougWebb]

At my old job our webapp handled 6+ million requests per day, and during the 8hr peak period it handled just over 100 requests per second. When you're dealing with request rates like that, even really brief periods of inconsistency will cause problems for someone.

We handled deployments a different way though. Each release went into a different directory and was made available under a different url, and users got redirected to the newest release when they logged in. Once in a session they stayed with the same version until they logged out. This also allowed us to do limited deployments; we could choose which version each customer group was sent to.