My Observation: Once a post ages, it will be thrown onto into post-purgatory, a heap of dead and forgotten posts, forever, while the discussion keeps going on the 10 newest posts max.
"Solutions" I found to this:
- look up admins of communities. What do they post? What other communities do they moderate?
- be patient with discovering new communities.
Integrating randomness might help, so old posts are not buried completely … add a random page similar to wikipedias special:random article. This might also help to get a feeling for the real average content in a community.