Think of a magnifying lens. Keeping the ideas within a dance channeled and related is a statement of tremendous artistic power, maturity and focus. It also need not be classical elements. Doug Elkins' Scott, Queen of Marys comes close to flying out of control with its fecundity of ideas, in total violation of the above paragraph. Yet, he holds the whole glorious salad in control, by keeping some elements recurring, and pacing the dance brilliantly.
Art is about the controlled flow of information, in space, over time.
Elkins holds his work in control by regulating the pitch of what occurs over time. Just at the moment when you think he might have gone on too long, the idea metamorphoses into something else. The tension is thrilling. When you next look at a dance, try to isolate its major physical themes or motifs. Think about the pace at which the choreographer unfolds the dance.