The Lesser Rogations which we keep on the three days before the Ascension are actually older than the Greater Rogations kept on April 25th. They are called “lesser” because they were instituted in Gaul ca. 470 AD, by St Mamertus, the bishop of Vienne, and only adopted into the Roman Rite about 300 years later.
Compared to other ancient liturgical rites, the Roman Rite is almost always very simple and even austere. In the Office of the Rogations, those who do not participate in a procession observe these days by saying the Litany of the Saints after Lauds; the Greater Rogation is not otherwise commemorated in the Office. Monday of the Lesser Rogations is commemorated only at Lauds if impeded by a feast; Tuesday is not commemorated at all; Wednesday is effectively occupied by the vigil of the Ascension. The Rogation Mass is the same for all three days, and very simple, with no Gloria or Creed, and one Alleluja between the readings; the Epistle is 5 verses long, the Gospel 9.
Compare this with the manner in which the Lesser Rogations were celebrated in the Gallican rite within which they originated. This is the schedule of Scriptural readings added to the Divine Office.
Monday
At Matins: Dan. 9, 2-19
At Terce: the Epistle of St James (yes, that means the whole book); Matt. 5, 17-26
At Sext: the First Epistle of St Peter; Matt. 7, 1-12
At None: the book of Tobias; Matt. 6, 1-13
Tuesday
At Matins: Joel, 1, 13 - 2, 11
At Terce: the Second Epistle of St Peter; Matt. 13, 2-23
At Sext: the First Epistle of St John; Luke 12, 15-31
At None: the book of Judith; Matt. 5, 31-48
Wednesday
At Matins: Hosea 5, 1 - 6, 6
At Terce: the Second and Third Epistles of St John; Matt. 4, 13-17 and 11, 28-30
At Sext: the Epistle of St Jude; Matt. 21, 28-32
At None: the book of Esther; Matt. 6, 14-33
This is the set of readings given in the Lectionary of Luxeuil (ca. 700 AD; BnF. ms. Latin 9427). Our knowledge of the Gallican Divine Office is very incomplete, and I don’t know enough about it to contextualize this, but of course, this is all in addition to the regular Hours, the Mass and the Procession.
The picture is folio 165v, which gives the rubric for None of Monday, “the Book of Tobit, to the end.” (The three full books of the Old Testament are not included in the lectionary itself, since they would have been read from a Bible, but the seven Catholic Epistles are given in full.) The script is typical of the Merovingian period, a kind of chancery script that has been described as the result of dipping a chicken’s feet in ink and letting it wander around over the page for a while.