It takes little time - and hardly any money - to download e-books when they are on sale, Mr. Lavalli said, making it easier to give up on a book if it does not keep his interest.
"You can read the first few chapters and say, this guy can't write," he said. "Then you throw it away."
Jim Hilt, the vice-president for e-books at Barnes & Noble's Nook unit, said sales generally peak on Wednesday and Thursday, when customers start planning for the weekend and thinking about which books they are going to read.
"Those are really good days to get the right piece of content in front of someone," he said.
Ms McCourtney, based in southern Oregon, said she was shocked to learn from her publisher in February that her most recent book, Dying to Read, was a best seller.
Ms. McCourtney, who has published 42 novels, said it was a career first.
"I had never madeThe New York Times best-seller list before, so I was delighted," she said. "It certainly felt good."
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