The rule given in Praenotanda #9 of the OCM is that either the Gradual/RP or the Alleluia/GA is used, as laid out in the Gregorian Missal.General Introduction to the Lectionary (Second Edition)
Sacred Congregation for the Sacraments and Divine Worship
21 January, 1981
23. The Alleluia or, as the liturgical season requires, the verse before the Gospel is also a "rite or act standing by itself."41 It serves as the greeting of welcome of the assembled faithful to the Lord who is about to speak to them and as an expression of their faith through song. The Alleluia or the verse before the Gospel must be sung, and during it all stand. It is not to be sung only by the cantor who intones it or by the choir, but by the whole of the people together.42
41. Cf. Institutio Generalis Missalis Romani , n. 39.
42. Cf. ibid., no. 37-39; Missale Romanum ex Decreto Sacrosancti Oecumenici Concilii Vaticani II instauratum auctoritate Pauli VI promulgatum, Ordo cantus Missae, Praenotanda, no. 7-9; Graduale Romanum, 1974, Praenotanda , n. 7; Graduale simplex, editio typica altera 1975, Praenotanda , n. 16.
The intention of the rubrics seems to be that there should be one chant between each of the readings. Very few places seem to pay heed.Gradual proper to each day. The first part is sung by the choir and the verse is given by the cantors. The choir then repeats the first part. During Eastertide, a first Alleluia is sung in place of the Gradual. When there is only one Mass reading, it is followed by either the Gradual or the Alleluia except in Lent, when the Alleluia is
always omitted, and during the Easter season, when there is a choice between two Alleluias.
how do people typically mess it up?
To participate in the discussions on Catholic church music, sign in or register as a forum member, The forum is a project of the Church Music Association of America.