Options, options and options
People love to choose, and you should provide a lot of photos for them to choose from, and this can surely boost sale.
This is particularly due to the nature of photography: a form of art. Different people will love different kind of photos and different styles of them. If you want to capture the markets of all these different customers, you will just need to provide them what they need.
In addition, the costs of increasing the number is low. You just need to take more shoots, which can basically be done in seconds.