I am a career City Letter Carrier. I can not tell you the hours, but I also worked as a “casual” employee for two years and the job was really more full time than part time. Also, the Rural Carriers in my office do not have to drive their own vehicles, but rather have postal trucks called LLVs provide for their daily routes. Plus, unlike City Carriers, Rural Carriers set their own hours as long as the mail gets delivered.
Here is what a day entails;
1. Case: sort magazine, catalogs, odd pieces of mail into route order while standing at what looks like a book shelf and desk.
2. Pull: take mail from case and load into trays.
3. Load: fill the vehicle up with parcels of all size and shape, mail from case and letters, which are machine sorted in route order.
4. Deliver: Most rural mailboxes are along the street, so delivery consists of grabbing mail from one side and putting in the box on the other, getting out occasionally to reload and walk parcels to door.
5. Unload: return equipment and outgoing mail to the post office.
That is an average day. Hope it helps and feel free to send me a comment if you have more questions.