They are not 100% flat out unrankable for combo colors and placing objects where skin elements are, but simply guidelines. If you can avoid them (such as combo colors to change from full white or black to a shade of gray), then try to. With object placement, sometimes like for me, it's in my style to make use of the entirety of the playfield which includes corners. Why? Because this is how I enjoy mapping: utilizing all the space that's available for me. From what various nominators have told me is that within justification they are not something to ever DQ for.