Reading this article, there is a line saying,
The gun lobby, led by the National Rifle Association, has for years systematically blocked plans to modernize the agency’s paper-based weapons-tracing system with a searchable database. As a result, records of gun sales going back decades are stored in boxes stacked seven high, waiting to be processed, against every wall.
When you look at the picture of the boxes of the records stacked against the wall, it is eight-high.
Is this kind of a metaphor how tall they(the paper of records of gun purchases) are against the wall? Or is there another meaning? (Googling by "seven high meaning" didn't produce anything).