Given that he mostly seems to travel by high speed train (ICE) every station he could possible end up unintentionally would be a relatively major one
Unless there was severe disruption, of course - since the lines have been so well standardised in Germany, ICE trains can travel on local lines too, so you could theoretically end up in the middle of nowhere if the train service was redirected mid-journey.
That's not guaranteed in Germany. Even places like Marburg have (had?) ICE connections passing through.
He sounds like a confident young man; not one who quivers at the thought of travelling.
Being a confident young man can be pretty disastrous if you end up in wrong place wrong time. "The world is my oyster" levels of confidence can get you in trouble really fast. Not that it is the most likely scenario in Germany, but it is not a place where you can completely drop your guards everywhere all the time. Though I guess he is aware of the risks and acts accordingly.