My last T2K campaign, using 4e, had a perfect storm of encounters that were the result of the random encounter deck. It put it in "«BLEEP»ING HARD MODE!!!".
It's worth noting that I did NOT reshuffle the deck; I shuffled it once, and drew only as called for. They got all the hardest encounters in the deck early on, and the resulting losses of gear and body parts were a major drain on capabilities.
Note also, the deck had been thoroughly shuffled, and the hardest encounters aren't adjacent in a shipping-order deck anyway.
This resulted in some very odd story situations... a radioactive cloud - they aim for a nearby barn. Reduces the rads... but half the party got radiation sickness.
Then the next card was radioactive rain - so two shifts in a row.
I was concerned that the radiation was a TPK waiting to happen.
It's not out of genre, but it is a case of a perfect storm. I wasn't unaware of the possibility, but the odds were "reality distortion field" level. Especially since, when they had backup, they didn't get the hard encounters. They were complaining about it, too.