Each chapter of my manuscript deals with a single author, and as much as I'd like to believe that all my future readers will pore over the eventual book from cover to well-worn cover, lingering over even its index in delight and edification, I'm assuming that most will actually come to it for just the one or two chapters most relevant to their own work.
That being the case, should I be writing for experts on each author, who don't need a lot of rehash? That has mostly been my strategy so far: I sketch out the bare outlines of the background issue in the text, footnote the shit out of it, and move along to apply or reinterpret the few bits that are important to the work I'm doing myself.
"Lord Whasisface's two years away from London remain the greatest mystery of his biography. We know X and Y, but there has been disagreement about Z [insert huge footnote]. However, it seems safe to assume that some part of Z occurred, for its imprints are all over his subsequent work."Or
"Scholars have traditionally read this work as either A or B [insert huge footnote]. A more complicated picture emerges if we look at [whatever the fuck brilliant thing Flavia has discovered]."
Again, I know there's no hard and fast rule for this, but I'm curious as to how the rest of y'all weigh the pros and cons of lingering over background context that, while perhaps interesting in its own right, is widely and even tediously familiar to a portion of your audience--but only skechily known to another, probably smaller portion.