The offset from the wall should be at least one third of the room height.
Alternatively, the offset from the wall is where a 20 degree line projected from the base of the wall intersects the ceiling.
An optimum evenness is obtained when the luminaire spacing is the same as the offset from the wall.
Wallwashers only develop their optimal evenness as of a minimum number of three luminaires.
The position of a wallwasher in a room corner should lie on the 45° line