[killtimeatwork]

> We did four releases a year, across the entire organization (so mainframe and more modern platforms), on Saturday nights/early Sunday mornings. There was plenty of testing but there was still plenty of errors only found on the day of, and rushed to fix in the wee hours or daylight hours of Sunday morning.

This way, you had bugs in prod for less than a day once every quarter, as opposed to having buggy prod all the time, as is common in organizations doing Continuous Deployment.