Late night releases are especially annoying for east-coast shops that have to wait for their west-coast customers to sign off before starting the release. Waking up a little early to do an early morning release is much nicer than staying up all night waiting for west-coast peak to tail off.

Day-time releases are not without risk, though. As you’re bringing nodes down for the release, you’re running with diminished capacity, so you’ve got to make sure the remaining nodes can handle peak load. Sometimes the release itself can trigger additional load (such as when external javascript version numbers are bumped, invalidating browser caches, or when image sizes change, invalidating CDN caches). The onslaught of traffic as clients refresh their caches can be enough to overwhelm the remaining nodes and send the site into a tailspin.