A generation or two before Trent, at least two schoalrs advocated for reforms familiar to 20th century Catholics:
37. Among those most concerned for the reform of the Church at beginning of the sixteenth century, mention must be of two Camoldelesi monks, Paolo Giustiniani and Pietro Querini, authors of the famous Libellus ad Leonem X(Text in Annales Camaldulenses, IX, Venice 1773, coll. 612-719) which set out important principles for the revitalization of the Liturgy so as to open its treasures to the entire People of God. They advocated biblical instruction for the clergy and religious, the adoption of the vernacular in the celebration of the divine mysteries and the reform of the liturgical books. They also advocated the elimination of spurious elements deriving from erroneous popular piety, and the promotion of catechesis so as to make the faithful aware of the importance of the Liturgy.
The difficulty then, as now, was to gauge how much awareness could be cultivated through learning, and how much–really–needs to be communicated through a deeper apprenticeship in the liturgy. It’s more than study. It’s about good example, about tone, and an intentionality in the way one approaches the Christian life. In other words, knowing Jesus, not just knowing about him. Living the faith in the entire body, not just the intellect.
38. Shortly after the close of the fifth Lateran Council (6 March 1517), which had made provisions for the instruction of youth in the Liturgy(Cf. FIFTH LATERAN COUNCIL, [Bulla reformationis Curiae] in Conciliorum Oecumenicorum Decreta, edited by the Istituto per le scienze religiose di Bologna, Edizioni Dehoniane, Bologna 1991, p. 625.), the crisis leading to the rise of protestantism arose. Its supporters raised many objections to the Catholic doctrine on the sacraments, to the Church’s worship, and to popular piety.
Of course they did. The early 16th century was a tragic time of scandal and false witness.
The Council of Trent (1545-1563), convoked to resolve the situation facing the People of God as a result of the spread of protestantism, addressed questions relating to the Liturgy and popular piety from the doctrinal and cultic perspective(*), at all three of its phases. Because of the historical context and the doctrinal nature of the matters dealt with by the Council, the liturgical and sacramental questions placed before the Council were answered predominantly from a doctrinal perspective. Errors were denounced and abuses condemned. The Church’s faith and liturgical tradition were defended. The decree De reformatione generali(In Conciliorum Oecumenicorum Decreta, cit., pp. 784-796) proposed a pastoral program, whose activation was entrusted to the Holy See and to the Bishops, which demonstrated concern for the problems arising from the liturgical instruction of the people.
* The Decretum de sacramentis DS 1600-1630) and the Decretum de ss. Eucharistia (DS 1635-1650), the discussions leading to the Decretum de sacramento paenitentiae (DS 1667-1693), the De doctrina de sacramento extremae unctionis (DS 1694-1700), the Docrina de communione sub utraque specie et parvulorum (DS 1725-1730), the Docrinna de ss. Missae sacrificio (DS 1738-1750) dealing with essential matters of faith on the Catholic doctrine of the Eucharist as a sacrifice, and on points relating to its ritual celebration, the Decretum super petitione concessionis calicis (DS 1760), the Doctrina de sacramento ordinis (DS 1763-1770), Doctrina de sacramento matrimonii (DS 1797-1800), the Decretum de Purgatorio (Ds 1820), the Decretum de invocatione, veneratione, et reliquiis Sanctorum, et sacris imaginibus (DS 1821-1825), have had wide application in the field of popular piety.
Please don’t misread me: liturgical study is vital. But to instill a love for liturgy that leads to a fully Christian life, much more is needed than a program of liturgical instruction. This may well be one of the most dangerous misperceptions in liturgical discussions in today’s Church. Rubrics can be learned. Books and passages can even be memorized by the human brain. But in prayer, be it liturgy or something else, it is about a relationship with a person, Jesus Christ. A willingness to encounter the Son, to listen for his voice and discern one’s path in life–this is essential. To think that mouthing the words at a cleric’s prompting after everyone has passed a test is enough is frightfully false.
Why did Catholic piety do more to form the Church in the Tridentine centuries? Because it was more honest, and it dwelled closer to the heart of a Christian life: getting to know Jesus and coming to follow him.
My advice as a parish liturgist: distrust any argument in favor of better catechesis and more knowledge.
The full document, the Directory on Popular Piety and the Liturgy, is online at the Vatican site.
Catholic Sensibility 
There’s an interesting bit in John O’Malley’s book, The First Jesuits (pp. 162-64), about the early Jesuits emphasis on individual mental prayer, and he mentions Erasmus’ ‘Modus orandi Deum’ and the Devotio Moderna too. Nadal wrote …
“Public prayer consists principally in the mass, which has supreme efficacy as sacrament and sacrifice. It also consists in other prayers commonly held in churches, like litanies and similar things. Private prayer is the prayer that each one does in his room, and it … should always take order and priority over public prayer because of its power, and it especially befits us because we do not celebrate public prayer in common — we do not have choir. This means that for the Jesuit his room becomes his choir.”