Borges once wrote something about his father’s library. As a boy, his father told him that he was allowed to read anything he wanted from his vast library, on one condition: that if he found himself reading something he wasn’t interested in, he should immediately put it back rather than try to finish it.
This is a liberating perspective that I try, and fail, to maintain. If I abandon a book it’s no failing on my part, it’s a sensible reallocation of my time based on improved information. Continuing to read something you don’t want to read, just because you started it, is a terrible dunk cost fallacy.
I generally try and stick to that perspective. I have no reluctance to just stop when I've lost hope it's worth continuing, or I'm not enjoying something. There's been a few I came back to years later and have been very glad I did. Or with more recent works where trilogies are more common, stop when it's clear the second isn't a patch on a promising first. My exception more than validated that I should never feel I "must" finish, that makes just stopping quite easy now.
The only exception I can think of turned out to be an exercise in extreme foolishness (and a little ignorance), that turned into bloody minded penance to finish the set come what may. Love Arthur C Clarke, loved Rendezvous with Rama, it really deserved a great continuation. Read Rama 2 and it was slow, plodding and amateurish whilst being a mostly terrible follow-on that ignored most of what was in the original. OK, even Arthur's allowed a dud, it has to get better.
Garden of Rama was far, far worse, plot so weak you cringe, bullshit characterisation and even the science was awful. Probably the worst book I have ever read, bar none. Wife assures me the only times I have had a habit of muttering or yelling at books were Rama 3 and 4, probably to "fucking get on with it", maybe to make sense. No detectable trace of Clarke in 3 whatsoever.
Fool that I am, I tried again with Rama Revealed. 400 pages of badly imagined, plotless, garbage science rambling, that's taxonomy and biology of alien spiders and essentially nothing else, followed by "oh shit, almost out of pages, better figure out a point to this drivel", so immediate pace and plot change to 50 odd of pages of a weak, cliched, poorly imagined wrap up of the "why" of all 4. Entirely predictable cliche as ending. Second worst book ever. So carrying on for 2.5 books was pointless self-torture.
Eventually found out, as it wasn't mentioned anywhere (it's tucked away on Lee's Wikipedia page, or was), that Clarke revealed he contributed only some ideas, Lee did all the atrocious writing on 2-4. Clarke on the cover is an outright con. Reread Rendezvous to cleanse my soul.
This is a liberating perspective that I try, and fail, to maintain. If I abandon a book it’s no failing on my part, it’s a sensible reallocation of my time based on improved information. Continuing to read something you don’t want to read, just because you started it, is a terrible dunk cost fallacy.