I agree, as long as the pictures have some type of relationship to each other, it would be considered a grouping and not really individual pictures.
I have some people who have purchased up to 7 of my photos and have an area of their house with a long hallway, where they hang all of them. I've been to a couple of those clients, and the way they lay them out and chose scenes that flow together, it seemed to work out well. They also chose all the same style frame when hanging them all on one wall.
I remember years ago on a talk show, it might have been Oprah
where they were talking about decorating. They showed how you can have a wall filled with family photos with all different color frames. They then showed the same photos hung on the same wall with all the same style frames of the same color, as in all the same wood tones, all brass, all pewter.. whatever you choose, as long as they were the same, the pictures then became the focal point, and not a wall filled with all colors of frames. It looked a lot nicer than the first scenario.