Personally I have no idea why anyone would want to do that, personally I leave shadows and highlights on 0 then adjust blacks and whites to get a bit more contrast. If you hold down ALT whilst moving the sliders it will show when it starts to clip (you can do this on shadows and highlights too). I will then if necessary adjust the highlights and shadows but I normally just use localised brushes to adjust the parts of the image that need it (eg faces/eyes). Processing is always subjective, why not just try on a few images, you can always go back to the base image if it doesn't work out. I also like to make a few virtual copies if I think an image would work with a different bit of editing.