Do you mean a general writing outline, or the type of outline we ask for when people pitch to us?
As far as pitch outlines go, most of the accepted submissions have just broken down their books by chapters, giving us a one-paragraph summary of each chapter. Some have pointed out moral development/themes/character arcs in addition to basic plot summary, but it’s not always necessary, as a good plot summary will usually get that across. And before we even offer a contract, we usually talk with the creator about how we think the book could be improved, what genre and marketing we would like to assign to it, editorial feedback, etc. It’s a pretty fluid process…that outline is just a starting point, really. Some outlines are MASSIVELY changed between submission version and the final version we think warrants an actual contract. But in order for us to be interested enough to talk to the author, that first outline needs to be pretty solid: a good story arc, broken into chunks that will keep readers coming back; compelling, interesting characters who have noticeable development; strong emotional core.
At least in prose, most of my authors have stuck pretty close to the final, editorial-approved outline, although they’re getting good at punching up each chapter and making it more exciting once they actually write it. We can do more “punching up” while we edit the roughs of the text, too.
The only book that’s constantly veering from its outline is Tokyo Demons. But that’s mostly a function of the size and age of the series…and the fact that I’ve worked in adaptation for a decade, so I’m used to starting with something and then constantly slashing it and rearranging the pieces. If we had another author like this, and she had the backlist to prove that we should trust her, that would be fine, too. But what I do is dangerous and stressful, and I wouldn’t necessarily recommend it. *lol*