Comment 4 for bug 1848550

I do think it's important to be able to have some way for the server to invalidate cached library settings, since when one of them is changed, it's often with the expectation that the change will take effect immediately. Even 12 hours could be too long in some cases.

Now, "immediate" is a relative thing; I'm not necessarily proposing that the client run a heartbeat to check for cache-invalidation every minute. However, I do think there needs to be something that the user can do to guarantee that they're looking at fresh values, such as the "Clear All" button that Bill suggests and doing a cache check (or invalidation) upon logging in to the staff client.