There seems to be some tendency of never-give-ups to cluster, but it's not absolute. It's common to have one founder who's super determined and another who is less so.

If the never-give-up is sufficiently convincing, that's almost as good as having all never-give-ups. He drags the rest along. The dangerous case is the startup that has all middle of the road founders. These have to get lucky fairly quickly or they give up.