If someone is somewhere in the mid-range of certainty, they are at least somewhat open to considering other possible understandings (on level 2) of a situation X (on level 1). If they are very certain, it will be harder for them to consider other understandings, but at least it will be possible. These clients are somewhat harder to work with than those with zero or very little certainty, and those who are more certain will be harder to work with than those who are less certain.