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 โฆ 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.
I would say 9 days is quite young. The oldest post on lemmy is 6 years old.
I use the web-interface, which by default shows you hot posts on the frontpage, you need to do some clicking to find newest comments/oldest comments but there is also no inbetween.