In a letter dated August 10, 1893, Clara Schumann expresses her approval of Brahms's Rhapsody in E-flat, op. 119, no. 4 in a somewhat cryptic manner: “But now to return to the allegro, how powerful the first motif is and how original and I suppose Hungarian, owing to the five-measure phrases. It is strange, but otherwise this five-measure arrangement does not disturb me here at all—it just has to be so.” While five-measure organization is hardly a defining feature of style hongrois, Schumann's depiction of it as “strange” and demonstrative of exoticism highlights the entrenched music-theoretical postulate that irregular phrase lengths—especially odd-numbered ones—are exceptional, or even deformational.

Despite, or maybe because of, this view, composers and theorists of Western art music have for centuries been fascinated by these irregular constructions, and have explored their use in practice. Heinrich Koch shows in Versuch einer Anleitung zur Composition (Rudolstadt and Leipzig, 1782–93) that five-measure phrases may be derived from four-measure basic phrases (by adding a one-measure extension to a four-measure phrase, for example), or may alternatively be understood as basic phrases when combining two- and three-measure incises. Nineteenth-century writers, generally more concerned about symmetry and organicism than their eighteenth-century counterparts, are rather more circumspect in their approach. For instance, while advocating the use of irregular phrases, François-Joseph Fétis nevertheless warns that five-measure phrases are “the weakest for the ear” because of the asymmetrical juxtaposition of two- and three-measure units. He mandates that five-measure phrases must be organic, not merely as a sum of disparate components, but also as one seamless construction that conceals its intrinsic asymmetry. Anton Reicha echoes this sentiment, positing that a five-measure phrase is legitimate only when it is an inevitable manifestation of the musical idea. Both theorists thus advise that five-measure phrases should be “true” rather than derived, and their inherent imbalance must be remedied by a larger sense of periodicity that arises from their repeated occurrences. In other words, as Clara Schumann says of the opening of Brahms's Rhapsody, a five-measure phrase “just has to be so.”