"Default send interval" (notifications_default_send_interval) has no effect?

from notifications.admin.inc, notifications_settings_form():

  $form['defaults']['notifications_default_send_interval'] = array(
    '#type' => 'select',
    '#title' => t('Default send interval'),
    '#options' => _notifications_send_intervals(),
    '#default_value' => variable_get('notifications_default_send_interval', 0),
  );

I'm trying to understand how and why this configuration item is used in the 5.x branch. I can't see any code in the Notifications project that makes use of this value, so I assume that this value does nothing in the 5.x-1.3 code base. Or have I missed something?