Why is this a great lesson?

The test is not repeatable. There was a power outage. Random machine configurations on random network conditions. These are all great ways to stress redis-cluster, which is still young, but they are not repeatable tests.

They are not great tests. Great tests would be a script that can run every 24 hours over a group of servers, simulating or creating similar events and network conditions. Then when a code change is made, you can actually observe if it made things better.

Driving a car across the Sahara Desert can be a good event, but it shouldn't replace Crash Tests in a Lab environment.