While I am glad that worked so well for you and your company. I had exactly the opposite example. Two years before Y2K we ran our systems forward to midnight 1999 and let it run past and had cascades of major crashes and failures. We spent the last 24 months rewriting and rerunning that same test on a set of test servers that the company purchased to run in parallel. Then we had to deploy it to production servers across ten time zones.

While in some cases it was overblown in others it was not, I was in the airline/support industry at the time. We could have shut down major airports and airlines if our stuff had messed up.