Mailing from coast-to-coast sounds like it would take a long time, but there are regular flights cross-country, and the sorting facilities bring mail to the middle of the coast, and then ship it straight across, east or west, depending. This means that the mail has to go first to a central sorting facility.
Truck and bus drivers must generally take a minimum of eight hours off between shifts, and their shift hours are often capped. Airline pilots are required to have 10 hours off between shifts to allow for transportation and rest time.
Lunch requirements. Under federal law, your employer does not have to provide lunch or coffee breaks. Also, your employer does not have to pay you for lunch breaks that you are given. However, your state might have mandatory meal breaks. The requirements vary, but many employees are guaranteed a 30 minute meal period per shift. To qualify, your shift will generally need to be 6 hours, and maybe even 8 hours long.