The following preference defines whether to link articles that have more images than the shape.
Skip Images When Needed
Tick this setting to allow that articles with more images get linked to the shapes with less images.
Example
The articles set contains articles with 1, 2 and 3 images, and the shapes set has shapes with 0, 1, and 2 images.
If you untick the option, the articles with 1 image will be placed only in shapes with 1 image, the articles with 2 images only in shapes with 2 images, and the articles with 3 images will not be placed at all, as no shape provides 3 images.
If you tick the option, the articles with 1 image can be placed in shapes with 0 and with 1 image, and the articles with 2 or 3 images can be placed in shapes with 0, 1 and 2 images.