While we have guidelines for release titles and track artists, we never got a guideline for classical track titles. So far most people are following the format of the data already there (and thus the existing pre-NGS conventions). That's mostly fine, but it should still be codified, and slightly adapted to take the existence of works into account (which allow tracks to follow the release a bit better).

Evolving draft at http://wiki.musicbrainz.org/User:Reosarevok/Classical_Track_Titles