The DBahn should have a disclaimer on their tickets, for the sake of full information. To wit: "The traveller should be warned, because of our combination of simple imcompetence and aggressive indifference to your need for timely travel, that you should completely ignore any ticket with a connection of less than 20 minutes. You will not make the connection, because we will probably dawdle and delay without warning or explanation."That disclaimer is probably on the tickets (or in the timetables) but it's in German. The official Interstate Commerce Commission approved formulation ran
The schedules, fares, and other arrangements in this folder are subject to change without notice. Every effort is made to have all information accurate, but the [Railroad Company] does not assume responsibility for errors in time-tables, or for inconvenience or damage resulting from delayed trains or failure to make connections.That noted, a twenty-minute connection on a regional railroad ought to be taken for granted. Six minutes on an inter-city connecting to another inter-city is a bit much. But the best timekeepers in railroading migrated to Chicago years ago.