When I'm reading Hemingway, I'll go back and read individual paragraphs three times to squeeze the last drop of juice out of them. There are only so many Hemingway paragraphs in existence, so wasting one feels like cramming an entire bar of imported Spanish 70% Artisan Chocolate in your mouth and washing it down with soda. Why would you do that???
Take Sordo on the Hill from For Whom the Bell Tolls. It's just a few pages about these guys shooting at each other, but there's so much crammed in there. You learn an awful lot about that guy, his feelings about this war, why he's fighting it, how he ended up on this stupid hill, and why he's going to go ahead and die there rather than any of his other options. He's a real person with complicated motivations and after a few pages you come away knowing pretty much everything you need to know about him and why he was acting the way he was earlier in the book.
Of course you could skim that scene in a minute flat and get the Hollywood Blockbuster version with the crazy local militia yelling stereotypical catch phrases and dying in a blaze of glory.
But then can you really say you read that book? Wouldn't you still want to go back and read it for real some time?