Maximum tile size for shower floor
My shower floor is 4' x 5' with a Kerdi drain in the center. The floor is sloped 1/4" per foot from the drain to the furthest point.
I'm thinking about using slate on this shower floor and I have received conflicting advice regarding the tile size. Some have advised not to go larger than 4" x 4", while I have also heard that I can go as large as 12" x 12".
From what I've read, the smaller size is recommended for two reasons. One, it will allow for more grout which will provide traction. But, slate has texture so perhaps extra grout for traction is not needed? Second, smaller tiles will make it easier to tile the sloped floor. But, with a 4' x 5' floor, could I make larger tiles work?
If I try to use larger tiles, is there a recommended layout which will allow this to work? And, is using slate on the shower floor going to result in maintenance problems down the road (eg water sitting in the crevices, etc)?