I don't recommend using raytraced shadows on all lights. It will drop the render time to a crawl and create conflicting shadows in most cases. The general rule of thumb is to turn Raytraced shadows on the main light source and off (all shadows) on other lights. There are times of course one does want to turn them on other light sources but one should do it judiciously and with forethought. At night in particular, one might have a reason to have multiple lights with shadows but rarely in daylight shots.