Chapter V looks at “Various Circumstances Relating to the Mass.” What can be said about them? They are varied, and largely pertain to the clergy:
[110.] “Remembering always that in the mystery of the Eucharistic Sacrifice the work of redemption is constantly being carried out, Priests should celebrate frequently. Indeed, daily celebration is earnestly recommended, because, even if it should not be possible to have the faithful present, the celebration is an act of Christ and of the Church, and in carrying it out, Priests fulfill their principal role.” [Code of Canon Law 904; cf. Lumen Gentium 3; Presbyterorum Ordinis 13; cf. also Ecumenical Council of Trent, Session XXII, 17 September 1562, On the Most Holy Sacrifice of the Mass, Chapter 6; Mysterium Fidei; cf. Ecclesia de Eucharistia 11; Eucharisticum mysterium 44; GIRM 19]
Would it be enough for priests to celebrate the Mass and the laity stay home? Believe it or not, a prelate at the Council of Trent suggested it. Daily Mass without a congregation may be laudatory, but it begins to shade away from liturgy and more into personal devotion.
Visiting clergy must have bona fides and prove they are in good standing:
[111.] A Priest is to be permitted to celebrate or concelebrate the Eucharist “even if he is not known to the rector of the church, provided he presents commendatory letters” (i.e., a celebret) not more than a year old from the Holy See or his Ordinary or Superior “or unless it can be prudently judged that he is not impeded from celebrating”. [Cf. Code of Canon Law 903; GIRM 200] Let the Bishops take measures to put a stop to any contrary practice.
Except when pastors have regularly scheduled liturgy in the vernacular, Mass may be in Latin:
[112.] Mass is celebrated either in Latin or in another language, provided that liturgical texts are used which have been approved according to the norm of law. Except in the case of celebrations of the Mass that are scheduled by the ecclesiastical authorities to take place in the language of the people, Priests are always and everywhere permitted to celebrate Mass in Latin.[Cf. GIRM 114]
In other words, a visiting priest can’t just swoop in and change a parish’s language to Latin.
Concelebrants must know the language they’re using:
[113.] When Mass is concelebrated by several Priests, a language known both to all the concelebrating Priests and to the gathered people should be used in the recitation of the Eucharist Prayer. Where it happens that some of the Priests who are present do not know the language of the celebration and therefore are not capable of pronouncing the parts of the Eucharistic Prayer proper to them, they should not concelebrate, but instead should attend the celebration in choral dress in accordance with the norms.[Dies Domini 36; cf. also Eucharisticum Mysterium 27]
Even groups outside regular parish structure must follow liturgical norms. We would expect no less:
[114.] “At Sunday Masses in parishes, insofar as parishes are ‘Eucharistic communities’, it is customary to find different groups, movements, associations, and even the smaller religious communities present in the parish.” [Cf. Dies Domini, esp 36; Actio Pastoralis] While it is permissible that Mass should be celebrated for particular groups according to the norm of law,[Cf. Code of Canon Law 905, 945-958; cf. Congregation for the Clergy, Decree, Mos iugiter] these groups are nevertheless not exempt from the faithful observance of the liturgical norms.
Except for the situation of clergy not being available, and the celebration of a communion service being forbidden or discouraged, I’ve never heard of this kind of thing being done in a parish:
[115.] The abuse is reprobated by which the celebration of Holy Mass for the people is suspended in an arbitrary manner contrary to the norms of the Roman Missal and the healthy tradition of the Roman Rite, on the pretext of promoting a “fast from the Eucharist”.
Watch your numbers:
[116.] Masses are not to be multiplied contrary to the norm of law, and as regards Mass stipends, all those things are to be observed which are otherwise laid down by law.[Cf. Sacrosanctum Concilium 36 § 1; Code of Canon Law 928]
It’s curious that there are concerns about too few and too many Masses.
What do the clergy ahve to say on this? This is largely about you.