From this site.
In theory, we are governed by all three instinctual drives, for they represent our most fundamental way of being, but one is generally more dominant and influential in our lives and defines the way in which we act out the passion of our Enneagram point.. If all three instinctual drives were in balance, we could function "perfectly" or "appropriately" to the needs of each situation. Nevertheless, such balance is rare, and usually one of these drives is "damaged" and commands an undue amount of our attention; and it is a person's most "damaged" instinctual drive that is overused and becomes dominant. The resulting imbalance distorts our perception of our essential needs, and we may find ourselves living large portions of our lives "in service" to this damaged drive.
So, question for those who have studied enneagram for a longer time than myself: is this the prevailing assumption or is it more specific to this site/this person (Katherine Chernick Fauvre)? I can’t say I’ve researched instinct variant extensively, but this is the first time I’ve seen this.