I think the New Posts feed could be improved by filtering the Challenge question answers out of it. They push out people's actual new comments and questions.
or additionally - create a new "new posts" feed that is focussed on unsolved questions only (i.e. not just unsolved items from ALL boards, but just from the Discussion Boards where people are asking for help)
To comment on this specific suggestion -- Thanks @StephenR for sharing! -- I see where your coming from. However, Weekly Challenge posts are technically new posts, so we can't remove those from the Community wide feed.