$wgObjectCacheSessionExpiry defaults to 1 hour, so users who have not interacted with the server for that long get logged out, even though their login cookies have an expiry of (by default) 30 days. This causes a lot of confusion, and seems to me like an unusual practice. Especially for the small wikis where the default value of the configuration variables is most important, I don't think there is a compelling security reason for logging people out after an hour of inactivity, nor is it likely that their server would be stressed by longer sessions. We should increase the default to a day, at least.