Sunday gospel readings in Ordinary Time are explained:
105. On the Second Sunday of Ordinary Time the Gospel continues to center on the manifestation of the Lord, which is celebrated on the Solemnity of the Epiphany, through the traditional passage about the wedding feast at Cana and two other passages from the Gospel of John.
Beginning with the Third Sunday, there is a semicontinuous reading of the Synoptic Gospels. This reading is arranged in such a way that as the Lord’s life and preaching unfold the doctrine proper to each of these Gospels is presented.
This distribution also provides a certain coordination between the meaning of each Gospel and the progress of the liturgical year. Thus after Epiphany the readings are on the beginning of the Lord’s preaching and they fit in well with Christ’s baptism and the first events in which he manifests himself. The liturgical year leads quite naturally to a conclusion in the eschatological theme proper to the last Sundays, since the chapters of the Synoptics that precede the account of the Passion treat this eschatological theme rather extensively.
Did you ever wonder why the Bread of Life discourse in John 6 was placed where it was?
After the Sixteenth Sunday in Year B, five readings are incorporated from John chapter 6 (the discourse on the bread of life). This is the natural place for these readings because the multiplication of the loaves from the Gospel of John takes the place of the same account in Mark. In the semicontinuous reading of Luke for Year C, the introduction of this Gospel has been prefixed to the first text (that is, on the Third Sunday). This passage expresses the author’s intention very beautifully and there seemed to be no better place for it.
Thoughts?
Catholic Sensibility 
I always found it interesting that the placement of the John 6 discourse in Cycle B occurs during the customary time of the wheat harvest in the temperate regions of the northern hemisphere.
I use the summer John 6 interlude to pound home the dogmatic Eucharistic doctrines of the Council of Trent. And since summer is the customary time for visiting other parishes while priests are on vacation, it lets me add a little dogma to the diet of other parishes as well.