Earlier quoted context omitted.
To be fair, once a century refers to average, it is by no means a guarantee that it will be a century before the next crisis.
To be even more fair, there's absolutely no reason to think these types of events are independent; there's good reason to believe they're positively correlated. This means once one happens the chances of it happening again soon are greater than before it happened. (But if you're lucky and it doesn't happen again the chances decrease further, giving you an average of 100 years between them again.)
or more likely, it happens, but because of prior experience, the event is no longer as calamitous as the first time.
Looking at the GFC in 2008, the monetary policy back then was too tight (hindsight 20/20 and all that of course), causing the recession to be extended longer than it would've.
This covid disaster would've caused a similar problem, imho, if the Feds did not loosen up like never before. It "solved" that same problem the GFC produced. Had the GFC not occured, the pandemic would cause a double wammy - a medical problem, and also a monetary problem.