notch size lage format

[lancenotalot]

I know this question has been asked before but cant find the post,
what size notched trowel would I use for 600x600mm tile on walls?Will 6mm give enough grip?
Walls are all as flat as poss and will be using powdered flexi adhesive.

 

[wap]

i would use 10 or 12mm notched trowel on that size tile

 

[LLA]

10mm or bigger Square not round notch trowel