On the subject of "true" repetition: one of things I like about is Ashberry's sestina "
The Painter" is that he doesn't use end-word variation/wordplay to reduce the repetition constraints. The end-words remain unchanged throughout: "brush" never becomes "brushes" or "brash". There are also no grammatical shifts -- from noun form to verb form, say. But it seems even tighter than this: "subject" always means the artistic subject, "brush" is always the artist's paintbrush, the "buildings" are always the same buildings and so on. "self-portrait" is the closest we come to a variation, but even there's no shift in meaning of the word "portrait": it still refers to a painting on the canvas.
I realise I've gone slightly off-topic by bringing sestinas in, so apologies for that.