I don't know what the Nocturnale Cisterciense contains, but the Benedictine Liber Responsorialis basically only contains responsories for (Doubles of the) 1st Class feasts, as well as all 12 responsories for each of the Commons. Their objective was not to give the full office of Matins for every day of the year. Notated responsories exist for sure, for the whole year, except possibly some local ones and ones from newer feasts.

Singing Matins in full (i.e. to their full melodies, not recto tono) every day was probably almost non-existent even at the end of the 19th century when the LR was written, aside from in Carthusian monasteries and maybe a handful of places here and there. But that is just a guess.

Right, I spent some time at Clear Creek, who still uses the traditional monastic breviary and thus still has a long Matins. They would chant it all recto tono on all Ferias, memorials, Sundays, and most feasts. The remaining feasts and all Solemnities (except for the Triduum and Matins of Christmas I believe), were divided into two "classes":

On the remaining feasts and lower-ranking solemnities, the invitatory was sung in full melody, while everything else would still be recto tono. On the highest-ranking solemnities, the hymn was also sung to its full melody, and the Te Deum also at the end, but everything else still recto tono. With the result that there is literally no time of the year, outside of Christmas Day and the Triduum, that any antiphons or responsories of Matins are not sung recto tono.

William Renwick's Sarum Chant project provides a practical set of simple antiphon tones and simple responsory tones for exactly this purpose.

Byzantine communities frequently do something similar when they perform matins/orthros.

Yes, I understand the point about investing time, etc. especially as it applies to the longer monastic Matins (12 psalms every day, 3-12 responsories on feasts). However, I have to observe that singing recto tono vs. full melodies as a way of observing increased solemnity is a not an authentic understanding of the liturgy, as the liturgy is meant to be sung to its proper melodies. Yes, practical circumstances may mean, in our age of musical illiteracy, that more effort is made on Sundays and feasts days to sing full melodies, but such practice was never meant to be a mark of varying ranks of liturgical days. If chanting full melodies was meant to mean this, then there would have never existed full chants - antiphons, responsories, hymns, etc. - would never have existed for ferias or minor feast days.

Again, I understand that some places have limited resources and/or time, but some places do have the resources and time to sing more liturgies yet do not, either because they subscribe to this false notion of increased solemnity (the liturgy itself, and usually also the chants themselves, account for different liturgical rankings), or because "well, we are not a monastery or a cathedral church" (that is a direct quote from the pastor at the FSSP church I used to attend often)...as if only monasteries and cathedrals are capable of singing a ferial Mass or lesser feast day Mass.

I guess to get more in line with the original topic, I am intrigued by this Sarum project and this "frequent" Byzantine practice. I am not aware, in the Roman or monastic tradition, of "common tones" for responsories. However, it is true that each of the 8 Gregorian modes has a sort of "outline" containing common melodic formulas which are used in the majority (but not sure of the actual percentage) of Roman/monastic responsories. But even these aren't really "fixed" either, because each of these "common tones" for each mode contain multiple opening, mediant, ending themes. As far as I can tell, Roman and monastic responsories would usually (but not always, and almost never in every responsory) deviate from these "common tones" on Sundays and feast days.

CharlesSA - our sources in well endowed cathedrals and large rich abbeys may not be typical. If you have less than two dozen monks farming mainly low quality land you will probably not have skilled and experienced cantors. Admittedly you will be a foundation from some richer successful monastery, and can send singers for training, but quality control was probably no better then than is is now, with all our advantages of rapid, easy communication.
Also note that degrees of solemnization ad libitum are not alien to the liturgy. This is the explicit purpose of the chants in the latter part of the Kyriale.