A franchise is a valid trilogy if the viewer enjoys enough of the entries to own them all, even if some entries are poor.

“I picked a franchise that's way more than three movies, and I loved enough of them to own all of them, if that makes any sense.”

A trilogy must have connective tissue through the entirety of the series to be considered a valid trilogy.

“I think that the tr a trilogy has to have connective tissue through the whole thing.”