Should the power and the ground wire have all exposed wire shoved into the slot where you screw it down?

Should the power and the ground have all exposed wire shoved into the slot where it gets screwed down? or is it getting enough power with even half of it screwed down because its touching some of the metal? hopefully you understand what im trying to say.
Should the power and the ground wire have all exposed wire shoved into the slot where you screw it down?
It is probably getting enough power, but I would screw it the rest of the way down so it doesn%26#039;t fall off.