The number of sentences appearing in the live use-cases dialog is not indicative of a term's statistical importance.
Because live use cases are intended to show contextual usage of a term, only complete sentences are chosen for live use cases. Many terms -- particularly on shopping or video sites -- may appear on a page but not be part of a complete sentence. Hence, it is possible for a term to appear on dozens of pages, but only appear on 2 or 3 complete sentences.
Secondly, a term's weight (importance) is determined through a much more complex set of calculations than simply the number of pages (or number of complete sentences) in which it appears.