While I haven't done a reviewer's guide, I have done white papers. The problem as a freelancer is you don't know just how much time a company's management will take on a project. Your contact often doesn't know either. With some companies, the contact acts as a real editor and stands between you and the layers of marketing staff and the executives above them. In some cases, I've received 'fix this' notes from up to half-a-dozen people all along the management chain.(reproduced with permission--well, it will be as soon as SJVN gives me it)To avoid this, I find it helpful to make it clear that 1) You'll only do corrections sent to you and vetted by the contact person. 2) Any work above and beyond a set amount of time and/or revisions will be paid for at an additional rate. If you don't include the latter, you may find yourself, as I once did, doing dozens of revisions on an assignment, which went from being extremely profitable for my time to one that was almost a waste of my time.
The problem spring from the managers' need to put their fingerprints on a project. And, that annoying belief by non-writers and editors that anyone can write and edit. So it is that their thoughts on how a piece should read is every bit as good as a writer who's been practicing his or her craft for a decade.
In short, the customer is always right in this kind of project. Unfortunately, in corporate writing you may be working for multiple customers and never know it until after you've turned in your first draft.
A short time later, Curt Franklin offered these wise details: