Ancient Authors’ Practices and Procedures

This post is a question, addressed first and foremost to readers who may be scholars and students of ancient history and/or the Bible, but also to others.

For some time, researching the interrelationship of the Gospels and the question of sources used, I’ve often found myself wondering about the procedures these ancient authors may have used. If Luke used Mark and Q, or Mark and Matthew for that matter (I make this latter specification since I hope Mark Goodacre may answer!), then how would he have worked on his own literary opus? Are we to imagine him with his sources stretched out around him as he wrote? Or would he have had one or more assistants, ready to read to him alound at request? Or some other method?

Do we have any ancient authors who have written about the procedures that ancient authors such as historians followed? Any recommendations on things that have been written (whether primary or secondary sources, ancient or modern) that answer this question?

Thanks in advance for your help!