The pastoral judgment takes into consideration the culture, strengths and limitations of the people of the parish. To change to another mass for ordinary time probably would hinder the singing of the parts of the mass. The musical judgment tells us about the musical content itself. There are plenty of songs available that are based on scripture text. The most important of these is the liturgical judgment.
Liturgical judgment is the consideration given to the placement of the music in the liturgy itself.
We have different seasons in the church, and within those seasons are feast days and memorials. Progressive solemnity tells us that the music should always reflect the season and the day, if possible. During Advent we sing of expectation and waiting for the Lord's return. We try to choose songs that most effectively reflect the season. Since Lent is a penitential season during which the symbols of the church are covered or removed, the music should also be less ornamental, with simple accompaniment, and the lyrics should follow scripture passages that are appropriate to the readings and the Gospels for Lent.