In Panels, one can configure caching for blocks/content panes/etc. The built-in method is Simple Cache, for which two settings can be configured: Lifetime and Granularity.
For Lifetime, one can choose a value from 15 sec to 7 days.
Is this lifetime a minimum or a maximum? In other words, if I set the Lifetime to 7 days for a content pane, will that content pane be cached for 7 days no matter what? Or will it be cached for 7 days unless it is updated?