No complete lectionary systems exist before the seventh century, althought there are references in the writings of the church fathers to certain readings being read on certain days. For example, we learn from Augustine's commentary on John that dhe book of Genesis was read duriing Lent, the books of Job and Jonah during Holy Week, the Gospel Passion narratives on Good Friday, the resurrection narratives on Easter, and the book of Acts during Easter season.Nothing too surprising here. But then there's this:
In fact, only with the development of a church-year calendar with specific days and seasons would a lectionary with pericopes even be needed; otherwise biblical books were read continuously. The earliest extant lectionaries are Bibles with marginal markings indicating the beginnings and endings of readings (p. 65).Now just because the lectio continua is earlier than the pericope system doesn't necessarily make it right. Once the church started multiplying memorial events in the life of Jesus and then adding saints days the pericope system became inevitable. I believe that some combination of the two is best. Use the pericope system during Advent, Christmas, Epiphany, Lent, and Easter, but between these read through whole books of the Bible. It may even be advantageous to take a year off of the pericope system now and then.