by being able to model things, you'd already set yourself apart from the endless stream of artists running our of school each year. you wouldn't believe the amount of applications we reject, simply because people are too addicted to zbrush.
I think at minimum, having a Linkedin and keeping it updated is a good thing to do. It's pretty much a database of searchable resumes where recruiters like to hang out, so it is helpful in that regard. You don't have to post a lot or try to "network" by commenting on things. Just have it, keep it updated, maybe post stuff…
I wouldn't say its time wasted, every application you make counts and most studio's really do keep your profile in their database for future opportunities. There is the perspective that a rejection means "portfolio is not good enough", "there are other artists better than you" and while this might be the case, its…