There seem to have always been specific additional hymns for feast days, but they have been suppressed to make way for generic ecumenical Protestant hymns. This may be hard to understand, but in the 1950's it was a sin to attend a protestant church, Vatican Double One opened doors, it was cool to be catholic but sing protestant.

when i posted something else landed on top. oh well. is this what you mean?

My understanding of the 1950's is that except for certain feasts which were customarily associated with certain hymns, most Sundays would have random hymns at the beginning and end of Mass. This is, anyway, our practice at the EF today. The hymns were theologically correct, indisputably Catholic--they made a special point to teach the doctrines the world found most controversial like the Immaculate Conception, the Real Presence of Christ in the Eucharist, even the Filioque clause. They were chosen from books given the Imprimatur and approved by the local ordinary. They were usually well-focused on the sacred mysteries or else on the liturgical season, proximate feast, the devotional month, or else were chosen from the Marian or general repertoire.

At High Mass, the customary Processional hymn was followed by the Introit, except on Sundays, when it was followed by the Asperges, which was followed by the Introit while the priest changed out of his cope and into his vestments for Mass.