I read an article this week wherein James Patterson spoke of his prolific writing - 10 releases a year.
Many well known authors, to boost their sales, have added "with" to their books and added the name of another author. Janet Evanovich has brought out several co-authored books which she stated helps to give new authors an audience. I haven't found anything that shows how much input she has in these books, but in my opinion they don't have the "voice" of Janet Evanovich. Clive Cussler has also published many books with other authors and I've found these also sadly lacking. So, it seems that each author has different levels of involvement when they lend their name to another author's work.
Back to James Patterson. In the article he said "Some people can't get past the word co-writer, but lots of shows and movies are written by teams, so it's not such a strange thing."
The first step for Patterson when co-authoring is he writes an outline. A co-writer does the first draft and Patterson finishes up with whatever other drafts are necessary (he writes seven days a week).
I personally have been disappointed with these collaborations by well known authors. Although having never read a James Patterson book, I can't comment on his. What are your thoughts on co-authored books?