@gabrispy The number of walls you can hit with PP is dependent on PP level and even if you max PP, you would have to place all of the walls in a formation that allowed you to hit all of them, its not exactly the easiest of things to do.
So unless you get a really good formation of all 16 walls off, its a bit of a waste.
The % damage scale of Ice Wall isnt huge either, so you would be missing very little damage.