Maybe, but sometimes, the second is still worth seeing though perhaps not as worth purchasing. I tend to be nice with seconds of movies that I REALLY enjoyed, willing to give them a try, though not expecting as much as the first. Sometimes I'm let down, but frequently enough I'm not. As for 3rds in a series, rarely do I see them. I figure if the drop from the first to the second is about 50% [worth seeing once, but nothing more], then the drop from the second to the third will be about the same, meaning 25% as funny as the first, meaning not worth watching even once.
That's kinda my habit on movie-watching when series are coming out.
Mummy 3... well, the second was good enough, IMO, that I'm still willing to see the third, which sort of breaks my theory, but maybe the first was just so darned good that even 25% of the first movie is still good enough to at least see once.
