Examples of three-part density were difficult to find on this CD. In general, jazz writers like to use at least 4 or 5 notes when harmonizing a melodic line. Three-part harmony can give a big band a lighter, "smaller band" feel.
In the example below, Eric Richards makes use of planing and quartal harmony - restack the first chord in this order: C, F, Bb. This melody has an impressive amount of power and energy behind it. Writing in comfortable registers is a sure way to get volume from a limited number of instruments.