If you don't push your system to failure, you can't really say you understand it. And anyways the precise failure modes under various conditions are important characteristics for stability/resiliency. (Does it shed load all the way upto network bandwidth of SYNs; allocate all the memory and then exit; freeze up with deadlocks/disk contention; go unresponsive for a few minutes then recover if the traffic dies off; answer health check pings only and not progress on actual work).