Actually I started doing them because I wanted to learn different writing styles. Since i'm a new writer I want to know everything I can. When I started I realized that when I got sick 12 yrs ago and was unable to be a mortgage underwriter anymore that by doing them it is a little like underwriting. I put the characters and plot and complete story together without seeing them. The authors provide me the book, I do not charge, I do them when I can and they are requested and I really have learned a lot about the styles that all different kinds of writers use its actually helped me to understand the mechanics of a good book.