I find myself against and for it.
N the “against” column is the experience of my first position as a director of church music: I succeeded a beloved but often ill choirmaster who in his last two years was more ill than well, the result of which was that the choir would often show up to sing a Sunday Mass and discover they had no choirmaster that day. They had a modest number of pieces on standby for just such a situation, pieces which got repeated airplay during that time. When I took over, the singers were ready to move on from that handful of somewhat overused motets and try their hand at new repertory. To my everlasting good fortune, there was a musicologist who had been singing in the choir for awhile and who took it upon himself to plan the music for my first couple of years, with the self-prescribed rubric of never repeating a piece during the choral season. The singers took well to this unending variety, I enjoyed the challenge of preparing new pieces each week and discovering the immense variety of musical options, and I came to the conclusion that as there are no repeated liturgies during the year, there should thus be no repeated choral motets. That is, every liturgy has its own unique set of proper texts (both musical, e.g. Introit, Offertory, etc., and priestly, e.g. the Collect, the Super-Oblata, etc.), as well as the readings designated in the Lectionary, and so care should be exercised in choosing repertory that reflects or extends the liturgical texts already provided by the church; since those texts vary from one Mass to the next, so too should the music vary from one Mass to the next.
Further in the “against” column is the ever-growing supply of choral repertory available for free online, mostly older music in the public domain. There is so much lovely and liturgically appropriate material that it seems a shame to repeat a piece when there is something else of equal beauty and fittingness available. Not only do I try not to repeat music during the choral year, but I also try to repeat very little music from one year to the next, which wouldn’t be possible without the plethora of online resources.
One might even marshall a theological argument in the “against” column, in that St. Augustine described the beauty of the divine as “ever ancient, ever new.” The liturgy is a great gift which is supposed to both reflect and direct us to the beauty of God, and so employing the music of centuries past may well qualify as “ancient,” while an ongoing exploration of unfamiliar repertory satisfies the criterion of “new.” (If a piece has never been heard at the parish before, it’s “new” no matter how ancient it is.)
I decided this year to carry this practice over into my organ repertory, as well, playing a different piece as postlude each Sunday, dating back to the start of Advent. (Of course, this is slightly more manageable due to the six-week break during Lent, where there are no organ postludes; but then it’ll be offset during the summer when the choir takes a couple months off, while the organ—and attendant postludes—will still be required!)
N the other hand, the “for” column is not bereft: there are a few times of year when there are lots of different liturgies in a short amount of time—e.g. the four different Christmas Masses in under 24 hours’ time, or the liturgies of the Triduum and Easter Day, comprising four (or more) unique liturgies in just four days. There is much choral music that could be used at more than one Christmas liturgy; this makes rehearsal time extra-efficient, when a piece rehearsed once is to be sung twice or more. Contrarily, there’s not much musical overlap from one to the next of the Triduum liturgies, but the sheer quantity of music to be sung recommends that there might at least be some repertory repeated year to year, so that the choir (which does not have an infinite amount of rehearsal time!) may be well-prepared for all the music it needs to sing during that stressful (but so wondrously rewarding) marathon. Hurrah for institutional memory!
Additionally, and I’m sure I’m not the only one to feel this way: certain celebrations don’t feel right without “that piece.” Christmas seems imperfectly celebrated without Victoria’s O magnum mysterium, for example, nor Easter without Lyra Davidica’s Easter Hymn (“Jesus Christ is Ris’n Today”). Whenever I have the forces, I do Lhéritier’s stunning, hauntingly beautiful Surrexit pastor bonus for Easter IV (Good Shepherd Sunday), and I know of more than one church that repeats the Fauré Requiem each year at the Mass of All Souls’ Day. There is certainly room for the choir’s favorite pieces, or the parish’s. (I also repeat a handful of my own compositions year-to-year.)
So I find myself mostly against repetition, but not dogmatically so. I try to vary the music throughout the choral season—and it’s always wonderful to discover new and beautiful liturgical music—but there is definitely prudence in recycling some choral repertory from one year to the next. Strike whatever balance best serves you and your singers and whoever else (if anyone—pastor? liturgical committee?) has a voice in shaping your parish’s music, while not neglecting the opening of Psalms 96 & 98: sing a new song unto the Lord!