What do you mean by "hymnifying the second half" or "fractal-like duck form"?
'hymnifying the second half' is what i sometimes call the thing in a traditional song form where the 4th 8th is the 5 chord, and the 8th 8th is the 1 chord, and the 7th 8th usually contains 1 over 5 and 5. you've heard it thousands of times. she'll be coming around the mountain, etc. Fractal like duck form is a phenomenon that occurs where the landing point of the first half is in the same relative time position as the landing point of the whole thing, relative to the whole thing. so for example, over the course of a 4 bar phrase of lyrics, let's say your first line lands halfway through the second bar, that's squarely on the 4th quarter of the first half. then your next line should have its landing point at the top of the 4th bar, which is the halfway point of the second half, and hence the start of the 4th quarter of the whole thing. so your landing point of the entire thing is in the same position relative to the whole as the landing poing of the first half was to the first half. this creates a fractal-like self-similarity that the mind responds very well to, and is present in many many lyrics/songs and rhythmic poems.