fun fact here that no matter how short the automated system is set up to alert, customers are faster - no one knows how is that possible
Can't tell you how many times I've had a customer write to me, only to be receiving some automated alerts 30-40 seconds later.
But as a counterpoint I was once working in a project where our monitoring dashboard showed an anomaly in incoming traffic. It turned out that it was an ISP problem and that we were the first ones to notice according to them.
So maybe part of the answer as to why customers are faster is that different monitoring systems are monitoring each other :)