In his book Daily Prayer in the Early Church, Paul F. Bradshaw lays out his landmark thesis about the historical interaction between the “cathedral office” and the “monastic office.” Perhaps more important than that, however, is the more basic observation he makes demonstrating that the role and nature of prayer itself dramatically changed in the 4th century. This change has more or less stuck with the church, informing its attitudes about what the worship service is, and, according to Bradshaw, not always in favorable ways. He explains:
The variety of practice in this early period raises the question as to whether any particular authority can be claimed for any specific arrangement of times of prayer. The emergence of the morning and evening hours as pre-eminent was, as we have seen, a fourth-century development which came about partly because of practical convenience and partly because they were seen as the fulfillment of the Old Testament pattern of daily sacrifice. If, however, the Christians of the first three centuries were right in seeing the true fulfillment of these sacrifices in the ceaseless prayer and praise of the Church, is there any particular justification in retaining these two offices as somehow normative for the Church at all times and in all places? Their dominant position has frequently been defended in recent years by the claim that they are the most ancient of the regular Christian times of prayer, but, as we have seen, if antiquity is to be the criterion for selection, then both night and noon have equal claim to be considered as of cardinal importance. Night prayer in particular, which has so often been neglected in the later traditions of the Church, at least as regards the hour of its celebration, is so intimately related to the New Testament eschatological thought that it cannot easily be regarded as of secondary significance in comparison with the morning and evening hours. Similarly the ninth hour, too, cannot be lightly dismissed, since it is the one time of prayer which owes its origin directly to an event of supreme importance to the Christian. Far and above all this, however, what is fundamental to the early understanding of daily prayer is that the real aim is unbroken communion with God, and the adoption of specific times of prayer is only a means to that end. This therefore suggests that there is no particular normative pattern of Christian daily prayer but that the times and frequency of such prayer very well vary in accordance with the spiritual needs of the Christian, as well as his or her cultural and pastoral situation. Set hours of prayer are not so much an obligation imposed upon us as a guide and aid towards the practice of ceaseless prayer, and when they fail to fulfill this function, their continued use may rightly be questioned.
A major characteristic of the set times of daily devotion in the first few centuries was prayer, and especially intercession for the needs of the Church and the world. This may seem too obvious to warrant mention, and yet it is the very element in the daily offices which steadily declines almost to the point of extinction. As often happens in the history of liturgy, secondary elements, in this case psalmody, gradually adopt a dominant role, and what were originally the primary elements assume a subsidiary place, and are abbreviated in order to give more time to the newer additions. In this instance the process was encouraged by the emphasis in monasticism on the office as intended for the individual spiritual growth of those involved in it rather than as a corporate act of the Church for the benefit of all mankind. Recent reforms of the office have not succeeded in reversing this trend, perhaps in part because of a widespread loss of faith in the power of intercession. All too often the concluding prayers and intercessions are regarded as an optional appendage to the office rather than its heart, and are the first thing to be omitted when the service has to be abbreviated or combined with some other rite. (150-151)
There’s a lot there, but the basic claims are that individual prayer was the original “priestly sacrifice” of the New Testament church, noon and night prayers were as ancient and important as morning and evening prayers, and that prayers of intercession for specific concerns relevant to local situations were the primary prayers. By the 4th century, a transformation began to take place which would change each of these, making a more formal and organized “liturgical service” the focal point. Dr. Bradshaw is not opposed to formal liturgical services, but he believes that they need to promote and enhance the real prayer-life of specific believers. If they become a hindrance or a replacement to that, then they are not doing what they were originally intended to do. He unpacks and explains all of this in more detail in his book.