What drives the financial impact of a site outage or performance issues is abandonment. It’s important to understand that visitors experiencing a Website with issues don’t result in lost revenue, per se. Only when those visitors don’t return, and/or go somewhere else is revenue lost. A shopper’s tolerance for errors is called “tenacity” in Web load testing parlance. Low tenacity shoppers bail from slow searches and hanging shopping carts in a dash.
If a load test had been run that adequately modeled the impact of the planned launch, the damage would have been done outside business hours and Target management would have been able to decide whether to make changes to their systems and retest, postpone or restructure the launch or just "risk it" and see what happens. We don't really think they ever had the chance to make those decisions. Surely they didn't conduct a load test that predicted such an epic fail. But should they have?
Realistic Web load tests model site usage and shopper behavior. Systems are deployed to simulate high levels of demand from multiple geographically disperse areas. Once the load is generated, the infrastructure and application’s response are watched carefully to identify bottlenecks and breakage points as the entire mesh of the Website’s interconnecting parts are stressed. Only this level of testing can accurately inform e-commerce teams of their preparation adequacy.