That led me to remember how Charles Dickens did his court-reporting duties ... In those days, some people were adept at shorthand.
About short-hand, you are right. Plus the fact that people listened better than we do, A person would jote down notes and then shortly afterwards, using these notes, commit their memories to long land. In fact, this is what I did in come college classes, and I think I came close to an accurate transcript of some lectures. Further, we have almost nothing from the hand of Aristotle. What we have are the notes of his students. Which gives me all that much more faith in the accuracy of the Gospel writers about the sayings of Jesus. This goes to the Gospel of John as well. Bishop Robinson has a theory that what we read is an elaboration/redaction of a proto-gospel in the hand of John the son of Zebedee by a disciple more skilled in the Greek language.