In an interview published at the time of the Fifth Symphony's first performance, Nielsen mentioned that he had been preoccupied with the question of the four-movement symphonic mould. It was an issue he had already addressed in the Violin Concerto (FS61, 1911), each of whose two buoyant movements is prefaced by an extended introverted prelude. And he would return to it throughout the 1920s, not least in the two-movement flute concerto. His explorations place him alongside Sibelius as one of the most intrepid seekers for new patterns of symphonic construction.

Building on remarks from Nielsen's own lectures, Danish scholars see this search in terms of a gradual move from an architectonic to an organic view of large-scale form, that is, from taking the four-movement mould as a given to allowing the drama of the musical materials themselves to generate a unique large-scale form. In the case of the Fifth Symphony, however, Per Nørgård is surely right to refine this idea by identifying a confrontation between the principles of organic growth and absolute contrast. The tempo giusto clearly disregards the traditional sonata-form first movement; but the remainder of the symphony takes into account the demands of the four-movement scheme, working out a tension between the organic and architectonic principles. Within the first movement the dichotomy between the tempo giusto and the adagio is so severe that at least one serious commentator has suggested it would be better to call them two separate movements (see chapter 2 above, p. 35).