Depending on the venue and the composer (some composers having been declared sacred), there are a lot more cuts and unperformed repeats than you might think from what you generally read. Lengthening a work gets a lot more attention than cutting it, especially if the cutter is using “tradition” as his rationale. (Toscanini said that tradition is the last bad performance, by the way.)

I don’t like to be dogmatic about it, but my first rule of thumb is that I don’t want to cut something to accommodate the presumed short attention span of the audience. Time is highly subjective. Most of us have had the experience of sitting through many hours of music or drama or film that seemed to fly and sitting through objectively short pieces that seemed interminable. In fact, in music, tiny shifts in tempo, resulting in 10 minutes more in a two-hour opera, can make a remarkable difference in our perception of time. The same thing happens when you stand in line at the bank for what is really “only” 10 minutes. And it happens for the same reason: Your mind is not engaged in the business at hand.

At the least, a repeat allows you to linger over an idea in much the same way that you linger in front of a great painting to watch new details emerge, or the way you glance back at a felicitous line of prose or poetry just because it is so well-turned. Repeats are also important to understanding the structure of a piece. A well-constructed piece, played in its entirety, will engage the attention and interest. Doing violence to the form can actually make a work seem meandering, uninteresting and, ergo, longer. Particularly in sonata form, when two theses are introduced, repeated, and developed, the repeats help you recognize and appreciate the development. It is satisfying, then, to follow the work to its logical conclusion. Continuity enhances the experience. The challenge to a performer is to keep his (or her) own attention span up and illuminate the work for the listener by continuing with intensity and expression and, perhaps, by introducing nuance. When something is good (e.g., film, play, song, aria, sonata, literature, painting), we relish repetition.

Oftentimes, a cut in opera is pretty similar to dropping a repeat (opera has far more written-out repeats), and I take the same approach. Hacking a two-hour opera to one and three-quarters or one and a half hours doesn’t make sense to me. But, the bigger the form, the more reasons there may be to cut. At about three hours, I’ll consider cuts more willingly. Even in those cases, though, there can be reasons beyond our expectations about the audience’s tolerance: economic considerations and the resources required of the singers. In particular, if a composer made later versions with cuts, they deserve our respectful consideration.