The Suttas are not 'sound bites' recorded as the Buddha spoke. They are compacted summaries of what was said, rehearsed and agreed upon by the Arahants at the Great Councils and memorised and chanted together by large groups of monks called Bhanakas (Reciters).
"Writing was unknown then, and so the Buddha’s sayings, as collected by his disciples, were committed to memory by a group of monks and were handed down to their disciples orally. There were probably two such groups, who, in order to distinguish themselves from each other, became known as Digha-Bhanakas and Majjhima-bhanakas. The other two Nikayas were later developments, their object being only to rearrange the topics dealt with in the Digha and the Majjhima". http://www.quangduc.com/English/history ... ars07.html
The Suttas are teaching vehicles whose meanings are densely packed layer on layer. They are not to be read as an ordinary page of print, but require 'unpacking' by someone learned in the Dhamma. This condensed form was necessary in order that the Teachings would not be lost in the years before they were finally put into writing ~ engraved on leaves in Sri Lanka. It allowed them to be memorised by the large groups of bhikkhus (bhanakas) assigned to each portion of the Tipitaka. They are not verbatim reports of chats and conversations. This memorisation is said to have commenced before the parinibbana of the Buddha. Anything that is repeated is to be seen as something important which was highlighted by the repetition.
The Suttas are rather like the memory prompts - the dot points of the most important information to be transmitted - similar to those a public speaker carries for reference.
"Thus you should train yourselves: 'We will listen when discourses that are words of the Tathagata -- deep, deep in their meaning, transcendent, connected with emptiness -- are being recited. We will lend ear, will set our hearts on knowing them, will regard these teachings as worth grasping & mastering.' That's how you should train yourselves." (Ari sutta).
.... with regard to the accuracy of oral traditions ... Anthropologists agree that oral teachings are generally more accurate and less prone to "improving" than are written teachings
The Pali Suttas are summaries of what the Buddha meant to be passed on - and great care was taken, while he was alive and afterwards, to memorise them in a form that could not be distorted, and by a method that did not allow of deliberate alterations to meaning and content. The recitations were going on for the forty five years of the Buddha's teaching life. The repetitions in the suttas are pointer to the most important parts.
Venerable Mahá Kassapa, the Head of the First Council. Cúlavagga Xl,1,1 (ii,284) reiterated:
"Come, friends: let us recite the Teaching and the Discipline before what is not the Teaching shines forth and the Teaching is put aside, before what is not the Discipline shines forth and the Discipline is put aside, before those who speak what is not the Teaching become strong and those who speak what is the Teaching become weak, before those who speak what is not the Discipline become strong and those who speak what is the Discipline become weak."
So the system was in place before the Buddha passed away. The Pali suttas are extremely condensed summaries of the Buddha's teachings, packed with meaning, which need to be unpacked by those learned in the Dhamma. They were preserved in that form to aid memorising and chanting by the large groups of Bhikkhus called Bhanakas (Reciters) i.e. Majjhima-bhanakas, Digha-bhanakas etc. Each group was allocated a small portion of the Tipitaka to keep pristine and pass on. This began even while the Buddha was alive.
It was only hundreds of years later in Sri Lanka, in a time of famine and warfare, with many bhikkhus dying, and with Buddhism all but wiped out in India, that the MahaSangha decided the Teachings needed to be written down. They were engraved on Ola Leaves. Many of us have been to Sri Lanka and have had the inestimable good fortune to have seen demonstrations of this being done at the ancient rock temple of Aluvihara Temple (where the Tipitaka was originally written down) in the Matale district 26 km from Kandy.