[Dr. Jacoby]

Although, I just read in the Williams biography that he considers improvisation to be the most important thing in jazz – at least from the musicians’ point of view (Williams calls it “freedom”). 🙂

Well, sure. I think the primary issue with jazz scores is that cues have to be timed to the visuals, so you typically get shorter cues, especially if we’re talking about TV shows, meaning less time for a soloist to stretch out; whereas live, or on a record, those kinds of time restrictions don’t exist. In jazz scores, improvisation will mostly show up in source cues, or sometimes in longer cues if there is enough space for a solo.