If they didn’t, the movie studios would have given up on them a long time ago.
But they haven’t.
They also know that to get someone to pay attention to what they’re selling they need to give them a sample first.
Like that food stand in your local mall, once you get a taste, you can make up your mind if it’s for you.
They say that a picture can tell a thousand words.
A collection of them, done right, can convey to your viewer more than that.
Think maybe having a free salesman working all over the internet would be helpful to you and your books?
And that’s only one book trailer.
What if you decided to create two or three for each book.
A teaser trailer, while you’re working on your book, to build anticipation.
And then a final one just as the book is being published.
Hollywood, does it. Why not you?