Well, no, it's not about them, but if the choir does the same thing over and over again, it gets sloppy and there's no growth, spiritual, musical or any other way. Not to mention, it really does bore the choir to tears. That's not to say that a standard repertoire isn't a good idea, just be sure there's variety. In my choir, we switch Mass parts by season, and do a collection of antiphons in Advent and Lent. They've been the same the last few years, but as they only come up once in the annual cycle, it's not so bad. We do two anthems a week as well, but this is the Mother Ship, as it were, or the "big house", so Holy Mass is a big more formal.
>>Not to mention, it really does bore the choir to tears. <<
Well, if the choir is bored, perhaps they should realize that they are there, not to entertain nor be the focus of the mass, but like everyone else, to relive the sacrifice of Christ on the Cross.
That’s what we are there for, lest we forget.