Interesting post and interesting answers.
One thing to remember is that "mounting a production" in 1916 did not usually
entail the sort of mammoth undertaking we are familiar with. If the opera
company owned a backdrop that was a "desert scene" for instance, it would be
used for Aida, Thais, Goldmark's Queen of Sheba, and any other appropriate
scene. The same for props and costumes, although the famous singers often
wore their own costumes, appropriate or not. You can see in the photos of the
time that the sets were usually a few painted backdrops and some standard
rocks, trees or whatever that didn't require huge machinery to move.
So repertory additions and changes were frequent, and mostly dependent on
singers being available and willing to learn new parts, etc. Also the
orchestra and chorus were, relatively cheap.
This said, I do think that the public expected more novelty then than now.
American audiences heard of new successes by Puccini, Strauss and Massenet and
wanted to hear them as well.