This one is a rule that’s being broken in our current times. The era of COVID-19 is providing rare situations for certain.
The exceptions don’t make the rule invalid, however. Most things are not unique; even large scale pandemics have happened and we might learn from those instances. For sure we can learn from our personal, more day-to-day happenings.
When challenges present themselves look for examples of previous similar happenings and see what you can learn from those.
Most things are not rare.