Concept-Relation ratio should be ~40 (10 ... 70).
That means average concept has ~40 cause-effect relations with other concepts.
Concept-Relation ratio is used by Memory cleaner routine.
Concept-Relation ratio is a system parameter.
I think it is good idea to have about 10 ... 70 relations for every concept (with average = 40). If there are too many relations then cause-effect relations table has be cleaned more intensively. If there are too little relations then relations should be created less intensively.