The PhotoPress plugin now has a new block called Child Pages which will create a gallery of the child pages of any post. This is very handy for photographers that wanton create an index page of their galleries.
You can make a page a child of another page in the Pages admin interface and the block will use the featured images of the pages to create the gallery.
You can also control how the child pages block gallery will look when published. There are control for the number of columns to display, padding between items, ability to apply a uniform crop to all images, sort orders and number of child pages to show.