Question about story length

Hi everyone! If questions aren’t allowed please delete!
I was just doing some market research (buying and reading various erotica from the Amazon Kindle store) and I’ve discovered something. Maybe it was just the kind of stories I was reading but they were long. And didn’t get to the erotic stuff until dozens and dozens of pages in. I thought longer would be better but it feels like they’re artificially stretching it out to get more money from Amazon since the books get paid by the number of pages read.
I guess my question is: would you rather read a longer book or a shorter one? The book I’m writing right now is rather short compared to what I’ve seen but it jumps into the erotic stuff after about 3 pages of build up and expositions.
I guess I just got so bored reading these really long books that the pay off didn’t feel worth it. What do you think?