Editors are a persnickety bunch, but not everything we work with is engraved in stone.
What we do work with are style guides: not rules but guidelines for everything from dash usage to chapter title formatting. When editors work with a publisher’s style, the guidelines are fairly hard and fast for that particular client.
The debate comes in when you have preference, or when the client, typically an author working directly with the editor as in self-publishing, looks to the editor to set the style for the manuscript. Then the editor has a chance to delve into the various style guides in his or her experience and apply them as seems appropriate.
LinkedIn groups and various discussion venues for editors such as provided by the EFA or Copyediting-L are regularly filled with lively debate on such issues of preference. Do we prefer spaced en dashes or unspaced em dashes? Do you add a comma after a phrase ending in a question mark that falls in the middle of a sentence?
Other debates are less procedural: Where is the line between copy editing and developmental editing? How much fact checking should a line editor do? Is a degree or continuing education certification necessary or even desirable for a freelance editorial career?
One of the joys for me in freelance editing is the flexibility in this regard. Each client has different expectations and guidelines, and I can alternate between assuring conformation to a publisher’s style guide and creating my own for an author.