During the season, I predominantly use CD as a resource. I don't usually need to ask too many questions, but when I do, CD can be an absolute lifesaver. There's always someone out there who can answer your question, and it's a great resource to have when you're confused and crunched for time. The rest of the time, though, I hang around to stay connected with the rest of the FIRST community. I can check up on all the crazy random people I've met, that way
As far as members from my team go, we have a few registered, but Jack and I are really the only active ones. The other couple just look in occasionally, or if we send them to see something particular.
For rookies, I would DEFINITELY encourage them to join and become active participants of the CD community. There's so much aggragate experience here that rookies can draw on, and the best way to access it is to become involved. You can get some of it from just observing, but it's not going to be as helpful as if you're actively participating, and asking questions.