Moderator-Why the 30 days on some schools, not others?

I was noticing in the Alphabetic list of schools that some of them have had their messages erased (after 30 days) but others have all their messages. Why is that? Thanks.

They aren’t really erased, they should be searchable. We’re looking at this, and will probably extend visibility farther back.

Hello Roger, I just feel like it makes it appear as though some schools are more “popular” than others - which can give the wrong impression I think. Thanks for your reply.