Final answer:
Repetition and reduplication are stylistic devices used for emphasis and thematic significance, whereas cohesion, clarification, and modality adaptation are fundamental for text structure and audience understanding. Thus, while repetition adds stylistic depth, it's not used as consistently as the other concepts in literature and rhetoric.
Step-by-step explanation:
Repetition and reduplication in literature and rhetoric do not serve the same frequency or purpose as concepts such as cohesion, clarification, and modality adaptation. Repetition is a technique where words or phrases are repeated to create emphasis or thematic significance, as seen in the iconic 'I have a dream' refrain from Martin Luther King Jr.'s speech or the recurring motif of the green light in F. Scott Fitzgerald's The Great Gatsby. While both repetition and reduplication can enhance a work's rhythm and help reinforce its themes, cohesion and clarification are fundamental to the structure and understanding of a text, and modality adaptation is essential for tailoring the language and content to different contexts or audiences. Therefore, while repetition and reduplication do appear in literature and speeches for stylistic and emphatic purposes, cohesion, clarification, and modality adaptation are more consistently present across different texts.