September 15 is the date on which annual raises take effect. This means that on the 15th, the payroll servers are swamped with people eyeballing their new paycheck breakdown to see what has changed.
And every year, on September 15th, the servers would become overloaded and people would be unable to connect. Instead they'd get a message like this:
Due to unexpectedly high demand, the payroll servers are unable to service your request. Please try again later.
We apologize for the inconvenience.
Unexpectedly high demand? This happens every year on exactly the same date! How could it be unexpected?
For a few years, I set myself a recurring task for August 15th that said, "Remind the payroll department to increase capacity for September 15th."
I don't know if my reminders helped any, but it appears that the payroll department finally figured out on their own the elusive pattern to their high demand days and added additional capacity accordingly. I no longer have to remind them.