Drupal website developers and administrators benefit from its built-in feature to periodically check if any of the enabled modules and themes are out of date. Drupal performs this check daily or weekly, when its cron job is run, automatically. If there are any modules or themes in need of an update, then on the admin area's modules or themes "List" page, you will see the notification:

On some of the Drupal administrative pages, you will encounter a great many checkboxes. This is especially true of the permissions page (User management > Permissions), which starts off with more than six dozen checkboxes for a vanilla Drupal 6 installation. Add a typical suite of contrib modules, and the number of checkboxes increases substantially. As a consequence, you may be forced to manually check or uncheck long sequences of checkboxes, which quickly becomes tedious and time-consuming.

One of the things I really love about Drupal 6 is its "Status Report" page, located at "admin/reports/status" (or "Admin|Reports|Status report" if you're drilling down through the menu system). This is my first stop whenever I think something wonky is going on with a site.