Amateur singers would surely need plenty of rehearsals to cope with SATB polyphony, though hymns should be easier. Do they have rehearsal aids to practice at home? Is there a core of interested singers who want to sing any chance they get?

If they have to travel to week evening rehearsals, could you try offering alternate weekday and Sunday-after-Mass rehearsals if there is at least an hour's gap between Masses? I assume they are always present at Mass, so not singing half the time does look odd. What happens when they don't sing as a group, does an organist lead the congregation hymns and they sing as part of the congregation?
If a significant number are working, they will only be available on Sundays, so not for example the Triduum.

People's lives are very busy. I encourage you to be thankful for their dedication and enjoy when are able to perform. I have been in parishes where this would have been like manna from heaven. It may change over time. You never know.

Quoth @Musicguy57:

People's lives are very busy. I encourage you to be thankful for their dedication and enjoy when are able to perform. I have been in parishes where this would have been like manna from heaven. It may change over time. You never know.

(leaving aside my objections to the term "perform" in a liturgical context)
To a certain extent, I can see this applying to rehearsals outside of Mass. I would submit, however, that applying it to our participation in the liturgy itself represents a fundamental disorientation of our Christian identity. Participation in the sacred liturgy - and especially the Holy Sacrifice of the Mass, the "source and summit" of our Christian life - should be a matter of the highest priority in terms of our time and energy.

The ambitious programme put forward by @SponsaChristi (and which I remember very well from my days singing at an FSSP apostolate) is likely something that would be impossible outside of somewhere like a cathedral or a traditionalist personal parish. In particular, if people's availability to rehearse or to practice independently during the week is limited, the music might need to be simplified to fit the available rehearsal time. But the very idea that a parish's choir would object to having sung Masses every Sunday throughout the year and that the pastor of the parish would allow their objections to stand would have me shaking the dust from my feet and leaving.

Choirs sing every Sunday at the European parishes I've been to.

Yeah and when they do take off it’s odd. St Mary’s in Sydney sings on the English model but takes Low Sunday off as a break. Understandable, but I’d take off the next two weeks instead and rotate among a small pool to ensure that the chant is offered. Ditto after Christmas.

Episcopalians sing less somewhat per service compared to my parish, but we have less ambitious individual pieces. Their cathedral here preps six weeks ahead during the school year. Summers, two weeks.

If I joined a parish choir I would expect to sing every Sunday, solemnity, Ash Wednesday, the Triduum, and anything else that comes up. I would also expect weekly rehearsals at the minimum as well as extra longer rehearsals during Lent and Advent.

Agreed - and this is why I would not join a parish choir. (even with leaving out the part about practising at home).

And if I'd joined what was billed as a special-occasion choir, and the director tried to change it into a regular parish choir, I'd be rather cross.

Personally I'd be amenable to the arrangement laid out in the opening post - but only if it was done with consultation and agreement, not just music director's orders.

But whether it's reasonable for the specific choir depends on the people involved, their relationship to the parish, and what other musical and personal commitments they have in their lives.

Re-reading, I can see that this started as a 'special occasion' choir and you want them to sing more often. I'm mindful of @MusicGuy57's 'be grateful' advice, you have a good starting point and you do have to negotiate from there on. My experience is limited, but I'm happy to express an opinion: 8-)

Are all the members guaranteed to be present at the same Mass every Sunday? If not, then as @PaxMelodius says it'll be difficult to get people to change established family routines, some like Saturday Mass, some 8am Sunday Mass, some 10, some 12. It seems like the best you can do is announce that you would like to pick one Mass to sing at every Sunday, having agreed with the parish priest and celebrants about the amount of singing required and the style and content, and ask for volunteers to work to that level and see if you have enough to form a parish choir. I don't know the scope of your project - a simple Low Mass in a country church or a full scale bells-and-smells High Mass in a city cathedral?

I can't see how anyone can sing even simple pieces together cleanly without rehearsal, so the second thing to agree is when a weekly rehearsal will suit. That will depend on how far people have to travel. Our chant choir rehearses for an hour on a weekday evening after 6:30pm Mass, the hymn choir rehearses for a half hour before 12 Mass. In our national chorus we rehearse 2.5hrs/week plus the occasional Saturday workshop and four times in orchestral concert week, so I'm more hardened to lots of rehearsal.

At rehearsal, you discover how well they know the pieces and start singing when you have a secure programme, whether that is the four-hymn set, or the Kyriale & Propers chants, and a polyphonic piece for Communion. Repeat the same programme every Sunday until the next programme is secure. In my little small-town volunteer choir in Ireland with a few experienced singers to support the rest, we use the same programme of chant and a unison hymn for a month until next month's is ready, but you seem to be starting from a base of more musically trained people.

As to whether easier polyphony is the answer, you have to talk to them. Do they like singing simpler music and more of it, or do they enjoy the challenge of a harder piece that needs lots of rehearsal before it's safe to sing in public?

So, you have no choir!

Now, of course you can foster a spirit of cooperation and goodwill, which goes both ways (I’ve been on the receiving end of not-nice behavior, and today I just sent an email that luckily was well received).

but it’s still not like these people get a vote. The bickering and drama here are stupid. This schedule is tame, they already get five months off (practically six). I have every sympathy for Ian and practically none for anyone else.

Boom. I’m going to save this comment to my notes app; I’d go further and add something about weekly rehearsals as well (or at least 2-3 times a month depending on who is singing what when).

It doesn't even necessarily have to be that complex! I just tell my singers that, if you need to take a weekend off for whatever reason, that's fine - just send me an e-mail letting me know so I can plan accordingly. Likewise for Masses during the week: let me know who's available, and I'll plan around who we have.

The point is: the music keeps going, week-in and week-out, regardless of who happens to be available on any given week.

I have been monitoring this discussion because it has similar issues to what I am facing at my own parish.

I think this discussion may be focusing almost exclusively on commitment while overlooking repertoire, formation, and pastoral leadership.

Sixteen Masses a year does not strike me as an excessive schedule. At the same time, the question is not simply how often a choir sings, but whether the repertoire, rehearsal expectations, and musical demands are aligned with the actual abilities of the singers.

In many parish settings, expecting regular home practice from every volunteer singer is unrealistic. Most parish choirs are not made up of trained musicians. Some members will never become confident independent part-singers, regardless of the quality of rehearsal aids provided. That does not necessarily mean they lack commitment. It may simply mean the choir's repertoire and expectations need to be matched carefully to the singers available.

Another factor is the distinction between a special-occasion choir and a regular parish choir. A group formed around occasional liturgies may not automatically embrace the commitments required of a weekly choir. That transition requires formation, recruitment, a clear vision, and support from pastoral leadership.

More broadly, a parish's repertoire is just as important as its level of commitment. Choirs are sustained not only by rehearsal schedules, but by shared musical memory, accessible repertoire, patient formation, and a realistic understanding of volunteer singers. A choir that sings every week but cannot sustain its repertoire or retain its members is not necessarily healthier than a choir that grows more slowly but builds a lasting musical culture.

I've written about these issues in more detail in A Parish Inheritance. Building a parish choir is not a single decision about frequency. It is an ongoing process involving repertoire, formation, pastoral leadership, and the long-term musical inheritance of the parish.

A Parish Inheritance