wiki login expiration

Can we make wiki logins persist for substantially longer? wiki.postgresql.org
appears to require a new click on the "log in" link every hour or so. The
cookie itself has a 30-day expiry, so I gather the server is expiring its side
of the state faster. GPT thinks $wgObjectCacheSessionExpiry is the relevant
mediawiki setting. Perhaps 30d (86400*30) is a reasonable setting?

The new "log in" click usually doesn't require new credential entry, because
the community login cookie is much longer-lived (>1wk). Still, it's an
obstacle. The wiki's behavior of showing cached content to logged-out users
makes this especially important. Visiting the open items page while
logged-out may not show the last many hours of changes.