I do developmental editing mostly, so I charge a flat rate to read once and build an action plan, half before and half afterwards. Then we contract to work through the plan, where the bulk of the editing takes place and for this I charge 25% up front, 50% after the developmental edit, and 25% on completion of the final proof. I find that authors appreciate the spread payments and the transparency this brings.
Perhaps there is some misunderstanding of the phrase ‘developmental editing’ used in this article. Given the number of hours necessary to process, dissect, and reconstruct a text of that size, it sounds like anyone who charged that lowly is doing the job for fun and has a spouse to provide for them–all the while devaluing the work of people who do this for a living. It’s really not ethical.
For my book, Career Change, I gave an early copy to people working in my department in the day job who I knew were dissatisfied with what they were doing. They came back with questions and suggestions for what to include as additional material. For The Healthy Writer, we asked medical doctors to read it as a sense check (even though my co-writer, Euan Lawson, is a doctor!)
Obviously there is a big difference. I actually started with screenplays (with some mild success) partly due to hearing that as long as you have a good story, the grammatical errors won’t be a big deal. Well, that was not true. Maybe if a producer liked the story or I was already established but every contest I entered always came back with feedback about the grammatical errors. Even if I won or placed as a finalist, I always received critique on that. Very little is spelling error, it was more about structure, etc.