I don't see a need for multiple "Old Topics" boards. CHM's forum just had one. "Old Topics" rarely get resurrected, or need to be searched, so it's OK to dump them all in one place.
Also, "6-Month Outlook" cuts across system types, and so should not be just a child board for Active Highway Systems. For example, it could be the right place to discuss a change likely to be needed post-activation for a system about to be activated. Or the forthcoming CA 11 freeway in San Diego, the first phase of which will affect an active route as well as an in-dev system. As with "Old Topics", one board covering all types of systems seems best, or at least good enough.
I don't mind early comments on my one in-dev system (usaca) if they occur to people without their spending much time, though I'd encourage them not to look for errors until the system's graduated to preview status. I'm also in no hurry to move that discussion here from aaroads, or to do that for usaak until I've addressed Si's comments and am ready to solicit comments from others.