I overheard a conversation at work today about the reading habits of some biddies that sit near me. They were arguing over how long you read a book before you decide that it's crap.
One of the hens asserted that the first 20 pages are all you should commit to. The second of the hens insisted that you should give it the first chapter, regardless of number of pages in that chapter.
I typically don't give up on a book at all. I've been known to stubbornly finish books that I found excrutiating. I don't know why I do that. I sort of feel as though I make a commitment when I start reading a book. You can't just give up after twenty pages, or a chapter. I've read some really bad books, and I've read some great ones that started out terribly. I can think of at least three that I now adore that I had to FORCE myself to keep reading. Some authors just take a little time to get going.