Two observations

One

I never read chapter titles. In fact, I often don't even notice that a book has them -- I'm two thirds of the way through The Hundred Thousand Kingdoms by N. K. Jemisin, and I only just realised each chapter has its own name. This has got me wondering about their purpose. Are they intended to set expectations for the chapter? How is my reading of the book affected by skipping them? 

It's probably too late to start with The Hundred Thousand Kingdoms, but next time I read a book with chapter titles, I'm going to try to pay closer attention. 

Two 

The odds that I will read a sequel decrease rapidly as time elapses since I read the first book. This is true even of books I enjoyed -- Steph Swainston's The Year of Our War is a good example. I loved it, but I still haven't got to No Present Like Time. 

I think this is because my expectations regarding initial confusion periods are different for sequels. When I'm reading fantasy and especially sci-fi, I expect to be confused while I work out the rules under which the story operates. That's cool; it's just part of reading those genres. 

When I'm reading a sequel, however, I expect things to be instantly familiar. My memory isn't excellent, so the only way I can guarantee that familiarity is if I just read the previous book in the series. And given a choice between re-reading books just so I can get to the next one, or reading something new, I'll usually just pick something new.

Is this a lack of trust on my part? Maybe. I imagine that every author is working hard to get me back up to speed at the start of a sequel, so if anything the initial confusion period is probably shorter than in the first book. I'm going to try testing this soon, hopefully -- I really want to get to Chill, the second in Elizabeth Bear's Jacob's Ladder series.

(Incidentally, I think this initial confusion period might be one of the barriers that keeps new readers from SF. I don't think the mainstream genres train you to cope with that feeling.)