I am redoing my shower, I replaced the walls with hardibacker board
(vapor barrier as well) and now I'm ready to tile. I noticed that
most showers use small tiles but I would like to use
16 x 16 tiles (Low water absorption). Is there any reason why we don't
see too many large tiles in walls? is there any tip I should know
before I do it?

Small tiles (2x2 or smaller) are usually used on shower "floors" to conform
to the slope of the mud bed to the drain. However, there's no reason you
can't use larger tiles on the flat walls. I used 6" tiles on our shower
walls, but have seen 12" tiles on many shower walls.

I measured up to the "second" row of tiles from the floor, then used a
straight edge (a 2x6 in my case) to use as a level reference. Then I worked
my way up the wall from the straight edge, using plastic spacers to ensure
proper spacing and prevent the tiles from sliding down before the mortar
set. The next day I removed the straight edges and cut the bottom row of
tiles as needed to fit between the floor and the second row of tiles.

Anthony