There are so many different views on using prologues. Some authors never use them, whereas other authors use them with every book.
We should first explain what a prologue is. In the simplest terms, it is an introduction to the book. This right here, is why some authors don’t use them and find them unnecessary. They feel the prologue could just be the first chapter in the book. As an author, I tend to disagree with this thinking. Sometimes the prologue is used to set up the story and has nothing to do with the story directly, but is crucial for the reader to understand the story. So if the prologue were to be chapter one instead, it may end up confusing the reader as they have no idea how it relates to the story.
For me, the use of a prologue is dependent on each story. Each story is different. Each story is told differently. Our Trilogy of the Wolf story has a prologue in each book, whereas the Hartland series, do not. I think it is prudent not to be absorbed in what everyone else is telling you to do. Make your own decision. It’s your story, it should be how you want it. Not what someone else thinks is best, unless of course, it makes more sense as a chapter instead of a prologue. This is where you must decide whether it was constructive criticism or just the way someone else would do things.
I personally enjoy the use of prologues as long as they are kept simple and are not more than 10 pages long. There are a few books out there with really really long prologues, which turn me off as a reader because I want to get to the story.
So, as a writer keep in mind your audience and stay true to yourself. Don’t let others sway you in how you write. If your book needs a prologue to help the story make sense, by all means use one, especially if it doesn’t entirely tie into the story. Use judgment on prologues and how they fit the story best.