In Matthew, Mark, and Luke especially, it is easy to compare stories which are double or triply narrated between them, and when we do we find those same stories have an interesting mix of being the same (even at the verbal level) and yet in other ways different (in presentation).
[A page full of examples is forthcoming.]
This is relevant given many synoptic differences are best explained by authors ultimately depending on flexibly-deliverable teachings (oral performances) to churches which are thereby rehearsed and passed down with control.1
Early Christian churches cooperatively guarded the stories of Jesus through regular group-rehearsals (when they gathered on Sundays), and zealously worked to preserve the accuracy throughout the various tellings of their treasured stories.
This is relevant because this sort of communal protection of history represents a very high-level of quality control; it was very well situated to faithfully preserve stories across decades and longer.
Knowledgeable Jesus-bio teachers regularly taught Jesus-bio to others with some measure of formality (as rabbis did to students).
A full page will analyze 10 arguments
This is relevant because the Student-Teacher method tended to be a fairly well controlled one with generally reliable results (especially considering ancient memory).