Speaking af Dorothy Dunnett, I tried King Hereafter and only got to 58% before giving up. I could not keep track of any of the characters and there were so many allusions to historical events that I wasn't familiar with I just was forcing myself to keep reading. I had read daily for several hundred days and it ended up putting me off reading at all for months. The book needs some character lists and a glossary or something.
The first thing she does in
King Hereafter is blend the mythology of Macbeth
and Godiva
and Guinevere
and Jarl Thorfinn into a completely baroque plot (you are
supposed to notice the parallels to Arthurian mythos; it is taken for granted that you've read
The Once and Future King).
The
second thing she does is dial up to 11 something she did only as a background effect in both the Lymond and Niccolo books. It is this: she uses a third person observer as a narrator. Ok, fine but so what? The trick is that the narrator is
exactly as smart and as informed as the least smart and informed person on scene. Therefore, when multiple characters are present, you get only a rationing of what actually happened. Therefore, when only the smartest and best-informed characters are on scene, pacing skips through fast, and with the very minimum amount of information required to keep both action and atmosphere sustained. In Lymond you see this with the Francis-Mallet , Francis-Oona , Francis-Pippa and Francis-Nostradamus pairings. In Niccolo you see this even more often, but usually only once or twice per book. In either case the reader can just barge through and be only slightly mystified, until it is all resolved.
In King Hereafter it is the overwhelming majority of the book. Point being - it is absolutely trivial to lose the plot because it is very intentionally
not being given, but must be picked out from incidentals using full, absolute engagement and a well-developed set of crossword-solver like skills. Think of it as a Macbeth & Thorfinn- themed novel-format crossword, and you will see that just having an index won't help much.