Do what thou wilt shall be the whole of the Law.
The first question, I think, is whether a given celebration of the Mass is being construed as a magical ritual, a religious observance, some combination, or something else.
If it is being performed as a magical ritual, then reasonable magical protocols should be used. If it isn't being worked as a magical ritual, then other considerations may outweigh.
Personally, I believe it should be done. This does not, however, mean that it necessarily should be done before profane witnesses. I have sympathy with the "it isn't in the script" point of view - but only to a point. In 11 years of performing monthly masses, I would always perform a Banishing Pentagram ritual before Mass - but completely out of sight of those attending (either in the room before anyone else was admitted, or behind the veil while they were convened out front - depending on the arrangement).
The official Temple of Thelema mass calls for preparation of the place (including a Lesser Banishing Ritual of the Pentagram and other prep) before anyone is admitted to the space, and then a Lesser Invoking Pentagram Ritual during the mass itself.
@Forever93 said
"I'm wondering if Jim (or other folks who had contact with Phylis and/or Jane Wolf) has any info on whether banishings were performed before Mass at the original Agape Lodge in AC's day; whether there is any reason to think that AC had a specific opinion in the matter; and whether it is practiced today within TOT, which as I understand it does celebrate the Mass."
I have no information on what was done either in Cefalu or Agape Lodge - I never thought to ask. If there is something, say, in Phyllis' biography of Jane, then I've forgotten it over the years.
"I'm also wondering, peripherally, about the role that Mass plays within TOT."
It's one of several public rituals that a warranted Temple is entitled to perform. The C.O.T. corporate by-laws describe it as "an official rite of religious celebration performed within the Temple of Thelema." It is related to the formal ecclesiastical hierarchy of Temple of Thelema and is part of the larger circle of sacraments which Hierophants and Bishops are entitled to administer.