A verbalized rule reads as a statement about a type: "<Student> must occur in <Enrollment>". What the rule actually says is that this holds for every single student, and both ORM and SBVR word it that way, so the rules now open with "Each".

The cardinality rule needed more than that one word. It only binds the instances that occur at all - it does not make taking part obligatory - so "Each <Student> must occur 2 times" would be claiming what the mandatory rule claims. It now carries the qualifying clause:

Each <Student> that occurs in <Enrollment> must occur there exactly 2 times.

"Each" is used only where the subject really is an instance: the cardinality, mandatory and value rules. The identification rule, the combination-is-unique rule, and the subset and subtype rules speak about a type or about a whole set, so they are left as they were.