I know a few different religious communities that sing it with exposition of the Blessed Sacrament on Thursdays, and this was a tradition going back pre-vatican II.

Personally I dont mind it outside of Corpus Christi, when you have to choose between other options at a NO mass and if it is used only at particular occasions.

The one sung on Maundy Thursday and Good Friday ("Pange lingua gloriosi proelium certaminis"

The "Pange" sung on Holy Thursday is "pange lingua gloriosi corporis mysterium".

Regarding "Pange Lingua" specifically, I program it in Latin sung to the usual melody as a short Communion hymn, between chanting the Communion antiphon and the main Communion song, about once every six weeks, but I only use verses 1 & 4 in that case because verses 2-3 are too closely tied to Holy Thursday and verses 5-6 to Benediction of the Blessed Sacrament. Verses 1 & 4 are about the Eucharist as Communion, so I think it's appropriate to use those regularly at Communion during Mass.

I do likewise with other pieces that are strongly associated with particular liturgical feasts. For example, the piece we sing during the foot washing on Holy Thursday is Peter Latona's setting, "Mandatum." I program that as an offertory piece throughout the liturgical year when appropriate, but only verses 5-6 because verses 1-4 are too closely tied to Holy Thursday. Doing so serves two purposes: 1) on Holy Thursday itself it's a familiar piece that people know and can sing since we've sung it throughout the year; 2) singing that piece brings to mind Holy Thursday and the foot washing in people's memories so that the whole liturgical year looks back and looks ahead to the Triduum. I've planned "Mandatum" as the offertory piece both on All Saints Day and on the Solemnity of Christ the King for that reason: Christ is the King of the Universe who washed his disciples' feet as an example of saintliness/holiness for them to follow instead of lording his power over them.

Another example of getting more mileage out of liturgical music is a new composition from OCP titled "The Word Became Flesh," by Orin Johnson. OCP has categorized that as an Advent and Christmas piece, but I think it's suitable for use throughout the liturgical year. I used it on the Feast of the Transfiguration this past summer, as well as on a couple Sundays of Ordinary Time when the Gospel reading or the second reading made it a good fit.

Back to "Pange Lingua," I think singing it throughout the year instead of only on Holy Thursday both allows people to know and learn the song so that it's familiar and easily sung during the transfer of the Blessed Sacrament on Holy Thursday proper, and singing it outside Holy Thursday creates an association in people's minds with the rites and the mysteries of Catholic faith that go along with Holy Thursday, giving more cohesion to the liturgical year.

Parish communities that only sing it during the transfer on Holy Thursday often find that people don't sing it because they don't know it. Well, if you only sing it once a year, it's hard for people to learn it and remember it.

On Good Friday we sing the Roman Missal's English translation of "Faithful Cross" to the tune of "Pange Lingua" during Adoration of the Cross.

Yet I wouldn't use "Pange Lingua" for the entrance text on All Souls Day; I don't think it fits as an entrance piece. Maybe for Communion.

I've programmed Toolan's "I Am the Bread of Life" for Communion on both All Saints Day and All Souls Day, to be sung after the Communion antiphon has been chanted. That repetition reinforces an association between the two liturgical feasts.

That's different from the "Tantum ergo makes your hair grow if you use it faithfully" text (tune: ST THOMAS (Wade)) . . .

We regularly use the mode III melody for the Tantum Ergo at benediction, that serves to keep up its collective congregational memory.

Pange Lingua . . . Corporis Myserium is a worthy and rich eucharistic text at communion time any time of ear. Use it often!

I find the the mode iii melody especially useful for wordy 878787 office hymns, as there are not many other swiftly moving melodies that our congregants know with this meter.

I think the Sarum variant of this melody works much better for English hymn texts and their ideomatic word stresses.

At requiems and All Souls, I use this melody set with that glorious translation of De Profundis Exclamantes ( the medieval requiem sequence), "Christ, enthroned in highest heaven."

I would dispute the idea that a eucharistic connection to the requiem texts is tenuous. The dead soul's claim to the Body of Christ stressed at the requiem liturgy. This is one of the primary claims of the liturgical symbolism. That's why, for instance, we surround the body with 6 candles, emulating the altar arrangement and offering him to the Father bound up in and as the Body of Christ. See this verse:

That which Thou Thyself hast offered
To Thy Father, offer we;
Let it win for them a blessing,
Bless them, Jesu, set them free;
They are Thine, they wait in patience;
Merciful and gracious be.

OMM— what a treasure trove. Thank you!

The text of Pange Lingua is specifically recommended by the church to be sung on Holy Thursday. Nor where is it otherwise forbidden. Accordingly, it must be alius cantus aptus where the text would be appropriate.

The editor of the 1940 edition of the Westminster Hymnal notes the addition of Latin hymns for use at Benediction and suggests that some of them might be sung by the congregation during communion 'in place of the customary motet'. Pange lingua gloriosi is included here. [NB by the date of the imprimatur we were 10 weeks into conscription for WWII, and had had compulsory military training for men of appropriate age for six months, so disruption to choirs was anticipated]

Occasionally, one finds a parish with monthly First-Friday/First-Saturday prayer vigils. If these include a procession at the start of their Exposition, the Pange lingua is certainly appropriate.