You see it is easier to just aim at a smaller circle than to aim at the center of it or at least for me it is. And one of the added bonuses of this is even though you might sometimes be just off the circle or on the side of it since the actual hit radius is larger than the image you wont miss it. It kind of sucks that you can't modify slider size, oh well.
EDIT: And I am too lazy to edit a lot of maps to a smaller CS :< .