It seems to me that a lot of source-criticism rests on noting various editorial mistakes, where the redactor lets his sources shine through a little too brightly and frankly does his job of redacting them really badly–the literary seams in Jn, the inconsistent doublets in Genesis, editorial fatigue in Matthew.

The thing that troubles me is how obvious some of them are. It is hard for me to think a reasonably competent editor (working by hand, mind you, where each edition of the text has to be deliberately written out, beginning to end and word for word) would leave such gaping holes in the text. It would be easy to understand if they were put together carelessly, or in haste, and composed by copy and paste, where whole blocks of text could be blindly copied without going through all they say word by word.

I suppose it would be easy to think that one particular redactor was particularly careless, and periodically fell into blind copying without consideration, but this seems to happen a lot, across books written centuries apart by different redactors, some of whom seem (otherwise) to be pretty thoughtful and sharp.

I can also imagine this sort of sloppiness cropping up if the redactor is working in a language he doesn’t know well–actually translating the text takes effort, and so he sometimes falls into copying text almost verbatim without carefully considering what each word means; and even when he is thinking about meaning, he may be sufficiently distracted by the linguistic issues involved in translation that he doesn’t pay attention to subtle details that might be in conflict. But then I would expect other evidence that the authors were struggling with the languages–perhaps such evidence is there and I’ve overlooked it.

Aside from errors, there is another issue, particularly clear in the synoptics–If I am rewriting someone’s written story, I’m not going to follow his telling verbatim. I’ll internalize the story (or perhaps each pericope) and tell it in my own words; I might copy certain memorable phrases from my source, but I won’t just slavishly follow them sentence by sentence making only minor tweaks. What we get (at points) in the synoptics is a level of word-by-word literary dependence that just seems bizarre without copy and paste.
So my questions:

Is there speculation about the sort of compositional work-flow that would leave these–sometimes glaring–oversights that seems to pop up all over the Scriptures? Do we find anything analogous in other literature?

The possibility that makes the most sense to me, at this precise moment, is that they didn’t think of themselves as authors but as scribes (e.g., Matthew didn’t think of himself as writing a new gospel based on Mark, but that he considered himself more a scribe–he was copying Mark, but “improving” the text as he went: “I’m making a copy of the Gospel of Mark, but I’m fixing the terrible Greek as I go, and also I have some other important material that Mark strangely omitted that I’m working in as I go, and while I’m at it, I am fixing his inadequate theology and making some structural changes to the work by moving things around).