... while inferring from the overall feel of the piece when and where the piece was composed, and what compositional frameworks the composer may be using, so that it can use the correct dialect.
Good chord symbols indicate not only function, but also the composer's intention.
Debussy probably needs different chord symbols from a 1930s Broadway tune, which needs different chord symbols from 1960s jazz leadsheet, which needs different chord symbols for a 21st century jazz composition inspired by Dave Leibman's See "A Chromatic Approach to Jazz Harmony", which is where chord symbols go do die. Seriously. Liebman's chord notation style for quartal chords is influential, if not authoritative.
Good chord symbols indicate not only function, but also the composer's intention.
Debussy probably needs different chord symbols from a 1930s Broadway tune, which needs different chord symbols from 1960s jazz leadsheet, which needs different chord symbols for a 21st century jazz composition inspired by Dave Leibman's See "A Chromatic Approach to Jazz Harmony", which is where chord symbols go do die. Seriously. Liebman's chord notation style for quartal chords is influential, if not authoritative.