Human memory is partial and imperfect. A novel narrated in 1st person often has more detail than could be remembered accurately or completely. I propose one of these two alternatives:
*A narrator with a very bad memory, with no apologies. In other words, a realistic narrator.
*A narrator with a picture perfect memory of every day, like Borges's Funes. This would be like a hyperrealistic painting including detail more precise then one could perceive through normal sight. This would lay bare the artifice of including a higher level of detail than the average human could remember.
Both would be artificial narrative experiments. The conventional way of doing it is also an artificial narrative experiment, but it seems realistic simply because it is conventional. I'm not sure what would be more interesting, exaggerating memory or dimming it out.
(I remember a Woody Allen movie, Hannah and her sisters, in which a character recites a poem by Cummings. In my memory, it was one character's voice, but watching the film again and waiting for the poem, I discovered that it was a character of the opposite sex than I had remembered. I even had an auditory memory of the actor, with a particular accent.) I think the poem begins "Somewhere I have never travelled, gladly beyond all experience, your eyes have their..." If I saw the movie again I would not be surprised if it were a different poem, or a different gender. I think that I remembered Michael Caine reciting, and being surprised that it was a woman, but even that memory could be false. I know that he goes to a bookstore and buys it for her (Diane Keaton?). The other day I was trying to remember whether she or Mia Farrow was in Annie Hall. Yet I can remember things like "nobody, even the rain, has such small hands.")