Re-reading books that you never finished in the first place

I changed majors and wanted to graduate in four years, so I chose English literature. I crammed the major so I was reading a lot of pages from a lot of books during short periods of time. I didn't finished a few books that weren't quick/fun reads. I felt annoyed about never finishing them, so I held onto them with the intention to finish them.
I am a third through Tom Jones, and I swear that I do not recall most of what I've re-read. I have a fairly good memory, so I'm puzzled by a handful of items. I totally recall lectures from the class, so I have a vague memory of some of the plot twists, but I really don't see "foreshadowing" to suggest as much.