The term "riffed through" is most often used to describe the act of casually flipping through something, typically a book or newspaper. Antonyms for this phrase include "studied," "analyzed," "scrutinized," "examined," "evaluated," and "inspected." These words suggest a more deliberate and careful approach to reviewing something, rather than a quick and cursory read-through. By contrast, antonyms like "skimmed," "glanced," or "perused" suggest a more casual or hasty approach, much like the original word "riffed through." The precise antonym chosen will depend on the context in which it is being used, and the level of attention or detail required in the task at hand.