This post seems to be older than 1 year— so keep that in mind while reading. It might be outdated.
The issue in this grievance is whether rural carriers are entitled to additional time when they make more than one pass to a locked mail box. The parties agree that a locked mail box should have a slot large enough to accommodate the customer’s normal daily volume of mail. The parties further agree that there may be instances during a mail count when additional time is warranted for making more than one pass to a compliant mailbox dependent on the particular fact circumstances.
via News Info.