It is. There is some sharing of interests: the House of the Issola also has a skill for proper behavior, as they are known for their diplomatists. But one would not seek, for example, a Dzurlord on a delicate matter.

[a flicker of sadness there, as if that brings up memories]

The Cycle is... one can say it is how it is decided which House holds the Orb, and, thus, rules the Empire. That is a simplification, however.