There's something to be said about first impressions. I know we aren't supposed to, but I definitely have judged a book by its cover (those retro sci-fi covers with the giant block print from the 80s? Run away, run far, far away!).
I have become pretty good at judging whether I will like a book or a series after the first book. Either I love the characters or I can't stand them, I'm entranced by the world/plot twists or I wish they were more complex. And occasionally I just can't stand how blatantly/subtly sexist or problematic a book is, and then I won't continue with that book or series.
Sometimes, though, I decide to give a series I didn't care for a second chance. The most striking examples are both of SJ Maas's series, Throne of Glass and ACOTAR. In both series, I thought the first book was okay, but I didn't fall in love with the main characters. I also didn't find the world-building all that interesting. But both books completely changed my mind with book two. The worlds suddenly became far more complex and interesting, as did the characters. I really liked how much Celaena and Feyre grew between the time we first met them and after they each go through their own personal gauntlet of horrors; seeing how much I loved them after book 2 made me appreciate exactly how far these characters had come since book 1.
Another book I gave a second chance to is Name of the Wind. I was initially kind of bored with the second half of the book, and I thought it was just awful in how the female characters were portrayed. I still have a few qualms about the women in that series, but after a re-read I found a lot more to like. The rich mythology and the care with which Rothfuss constructed his world were magnificent, and I did like Kvothe a lot better when Nick Podehl was bringing him to life on audio. Somehow lines that seemed really strident and obnoxious in my head became a lot less annoying when read to me by someone who believed in the story. Wise Man's Fear though...that's a whole 'nother beast. My thoughts on that book are long and complicated, and best summed up by my rambling review.
Although I really love the Gentleman Bastards series, I initially didn't like Sabetha when we met her in book 3. She seemed whiny and petulant and I didn't like how she messed with my expectations of how a fictional romance was supposed to play out. A few years later I reread the book though, and I loved how utterly human she was. I was able to much better appreciate exactly how feminist the portrayal of Sabetha was once I became more aware of how my own ideas about women's roles and personalities in fiction were shaped by the expectations of the world I live in.
I guess my point is that I've come to realize that giving books a second chance isn't a bad idea. I am now way more open to giving books and series a second chance, whether that means re-reading a book I didn't like so much or giving the later books in a series the benefit of the doubt.