The more titles you have, the more books you sell. Having multiple titles also improves your author profile and reader loyalty.
Whatever marketing you engage in, be it blogging, social networking, podcasting etc., when your audience is led to Amazon (or wherever your book is sold), readers can only buy a single book once.
When you have two, three, or more books then you have multiplied the effectiveness of your marketing efforts - leading back to not one, but multiple buying choices, thus increasing sales: This is simple maths.
Less obvious is the way potential readers perceive an author who has multiple titles. If you have one book, people may buy it on the strength of a beautiful cover but if you have multiple books, or a series, it can instantly be seen that your first book wasn’t enough to satisfy demand and so more were written.
So that’s two good reasons to write more books, but there’s more. Readers are likely to invest emotionally into a series or a collection of books by an author. The rise in popularity of TV box sets over one-off movies is due in no small part to the fact that people increasingly consume and enjoy serialised media.
It’s no different with books.
“It is a pleasure to find such a courteous and speedy service in this day and age”
Bridget Beresford, author of Knights Without Armour