Kafka writing “in einem Zug”: not “on a train” but “at a stretch” or “in one go"

On 23 September 1912, Franz Kafka wrote in his diary about writing "Das Urteil" the night before "in einem Zug". In Ross Benjamin's new English translation of Hans-Gerd Koch's 1990 edition of Kafka's diaries, the passage reads (as quoted by Frances Wilson in "The New York Review of Books"): "This story 'The Judgment' I wrote at one stretch [in einem zug—literally: 'on one train'] on the night of the 22 to 23 from 10 o’clock in the evening until 6 o’clock in the morning." But that's no train: doing something "in einem Zug" is like swallowing a drink in one go – just as Kafka wrote the story "at one stretch." (Andrew Shields, #111words, 31 August 2023)