He or she should be able to almost unconsciously find and operate your link buttons. Student authors should also present a graphic theme. Thus, I have the planet icon you see. The reader might get confused. Fonts, headers, and subheaders should remain consistent.
Good design is pleasing, but it also something that quickly slips into the unconscious.
Think of a beach. You do not at every moment stop and admire the sound of the waves crashing in. The sound drifts into your unconscious, but nevertheless, remains pleasing. And, they are right to some extent. Not everything on the page need be the same.