OK this reveals my relative ignorance in choral matters, and the answer “it depends” also works; you can only work with the physical space given.

But what goes into the formation which you use to sing chant (particularly the propers) and where you stand? Or what would you do if all things were equal and you had total freedom?

— some directors prefer more of a semi-circle or even a U.
— others have more of a circle (particularly with four to eight or so singers)
— some directors stand in front of the semi-circle, at a small lectern or stand or holding their score. Others are in the semi-circle at the middle point (again, with or without a lectern — I notice that if the schola sings from a giant score, the conductor tends to sing in the middle)
— do you change for the Ordinary or other things where the schola doesn’t carry all the weight?

We are extremely space-limited but are trying new things, and I am noticing that somehow it’s better for my listening with people distributed in a wide semi-circle versus a circle.

There is also the conundrum of Vespers, or the Ordinary in a monastery or seminary, which ideally is sung by people in two parallel lines (and two or more rows potentially on either side).

I have drawn examples of what I mean.