hmm, i feel you some what contridicted yourself there. To me a rhyme scheme would stay the same thru the entire peice.
But a peice with out a signifigant rhyme scheme allows alot of switch ups a few pause's,samples used. diffent echo's and all sorts of shit, allthough, a solid exact perected rhyme scheme will create a stable solid flow, but if your not dropping some deep fucking originaly bars and just dropping played concepts,that shit will be reapeditive sounding and peopel wont take as much notice of you,compared to a track with a few solid flow switches, and alot of extra shit (not over done)