Thanks for sharing your story. It's very true that most of the times we do not bother to check the time of the clock before scheduling stuffs.

We maintain IT infrastructure for a big pharma company. For any SLA (service level agreement) breach, my employer has to pay a real big amount of money to the client. Now that's been told, once my colleague had to schedule a maintenance on an AIX server. We have a procedure to do that. There's a lot of approvals from service delivery managers of both the client and our company required. After getting those, this guy went on scheduling the reboot of the machine in maintenance mode in cron a day before. The next day, I got a call from IT Incident management people saying a server is down before it's scheduled maintenance window. It happened around 20 minutes before the scheduled time. We had to raise a severity for this. Upon checking the root cause of this later, we found somehow the server was failing to sync with the NTP server and the clock was going 20 minutes faster than the actual time.

And yes, because of all these, we breached the SLA!