I can understand some restrictions to prevent spamming, but it would seem like the newbie only forum + 4 hour wait seems like a pretty good middle ground there.  Maybe 30 or 60 seconds between messages too (like most other forums).  That's enough to stop spammers, and require a little bit of thought on your posts, but 6 minutes is way too long.  I can quite easily compose meaningful and useful responses to threads within 60-90 seconds.  Again, if I'm forced to wait then I'm more likely to go do something else and forget to come back.