The standard answer to this question is, it depends.
The best way to figure this out for your configuration is to do a “planogram”, or dimensional drawing of your walls and fit proportional squares onto the drawing.
With modern technology, you can use an illustration program like Adobe Illustrator or Canvas to create a 2D drawing of each side, and rectangles for each of your picture sizes. Clone the pictures until you have an arrangement that works for you, then count.
If you are not facile with illustration programs or the computer you can do the same thing with graph paper. You can also download and print the following illustration:
A few points to consider:
Not all walls will hold the same number of framed images — Propanels are generally 12″ above the ground. Gridwalls may go all the way to the ground, but the lower sections are less visible to the public, and you may not want to hang pictures that low.
A taller booth with panel extenders will hold more pictures. For example, a 9′ Trimline with 9′ panels has 20 square feet more of display space, per wall, than a 7′ Trimline with 7′ panels. If you are using 6′ panels, it will obviously be even less.
If you’re leaving a doorway in the back of your booth, that also decreases your display space.
It will also make a difference as to whether you hang vertically or horizontally.