Yau5 is Equal to yau6.
At yau5 you Bild 2 F2L Slots After you have done the 5.-8. Edge so you can do the Last 4 edges without cuberotations in the 2 left F2L Slots.
I just call it Yau5 because there's no change in the method for anything bigger than 5x5x5. I think calling it Yau6 would be like calling CFOP on a 6x6x6 CFOP6 which we do not do. (Or any other 3x3x3 method on a bigger cube for that matter.)