In many occasions, I have attempted to quick fill both small and large areas and the command has not allowed the task to be completed as it says the coordinates are outside of the world and cannot be placed. For instance, if I command, '/fill -224 69 -80 -35 69 85 stone' the response will show as 'You cannot place blocks outside of the world'. This happens with all sorts of coordinates and the command can be completed sometimes in different areas or from different coordinate points that cover those of the previously attempted command. This happens on both infinite and superflat worlds. The areas that are too big do state that they are too big still and the areas that are fine, that are accomplishable, reliant on the command going ahead, do still fill. It happens with all sorts of different blocks also.