I’ll check the GIRM, but I believe singing the Our Father at EVERY Mass is not endorsed.
From the GIRM:
40. Great importance should therefore be attached to the use of singing in the celebration of the Mass, with due consideration for the culture of the people and abilities of each liturgical assembly. Although it is not always necessary (e.g., in weekday Masses) to sing all the texts that are of themselves meant to be sung, every care should be taken that singing by the ministers and the people is not absent in celebrations that occur on Sundays and on holy days of obligation.Remember that I was speaking of a Sunday Mass. Where it says the it is not always necessary to sing all the texts of the Mass it not the same as discouraging it. The GIRM references no. 7 of Musicam sacram: Instruction on Music in the Liturgy (1967):In the choosing of the parts actually to be sung, however, preference should be given to those that are of greater importance and especially to those to be sung by the priest or the deacon or the lector, with the people responding, or by the priest and people together.
7. Between the solemn, fuller form of liturgical celebration, in which everything that demands singing is in fact sung, and the simplest form, in which singing is not used, there can be various degrees according to the greater or lesser place allotted to singing. However, in selecting the parts which are to be sung, one should start with those that are by their nature of greater importance, and especially those which are to be sung by the priest or by the ministers, with the people replying, or those which are to be sung by the priest and people together. The other parts may be gradually added according as they are proper to the people alone or to the choir alone.Latter in that Instruction we find:
27. For the celebration of the Eucharist with the people, especially on Sundays and feast days, a form of sung Mass (Missa in cantu) is to be preferred as much as possible, even several times on the same day.Prior to the council the was a strict distinction between the sung Mass and the recited or Low Mass. In the former all the parts, including the readings, had to be sung. In the later none of the Mass parts could be sung; the music being the addition of non-liturgical hymns. The reference to the sung Mass (Missa in cantu) is to a fully sung Mass. Thus the fully sung Mass is to be preferred on Sundays and feasts days. Masses with various degrees of singing is a concession to practicality and not an ideal to strive for.28. The distinction between solemn, sung and read Mass, sanctioned by the Instruction of 1958 (n. 3), is retained, according to the traditional liturgical laws at present in force. However, for the sung Mass (Missa cantata), different degrees of participation are put forward here for reasons of pastoral usefulness, so that it may become easier to make the celebration of Mass more beautiful by singing, according to the capabilities of each congregation.