# As an RCA, you don't get any benefits because you are classified as a 'part-time' employee (even though you may work 60+hrs/week). Getting a 'permanent' carrier position requires waiting in line behind any other substitutes hired before you- many in my office were subs for 6 to 7 years.
# Once you learn the routes and customers, I found the job to be rather tedious, both mentally and physically. Joint stress is a common complaint because of all the repetitive hand/finger/wrist movement. My preferred analogy is comparing the job to a hamster wheel because you do pretty much the same thing day in and day out with little or no sense of progress.
# Some districts and offices began delivering Amazon parcels on Sundays. If you are a "sub" (RCA or CCA) stationed at one of these offices, you may be required to work every day of the week. If your office doesn't have a good ratio of subs-to-regulars, you might regularly work 3 weeks straight without knowing when you will finally get a rest day (because you are on-call).
# The LLV mail trucks are all 20+yrs old and show their age from lots of hard driving- they can be a bit scary, especially on the freeway, or in remote areas. Fortunately, new vehicles are in the works, but there's no telling how soon they will actually be built and distributed to the thousands of offices.
# Learning and navigating a bunch of different routes can be very hard, depending on whether there are any maps, "Line-of-Travel", how much pressure supervisors are giving, how heavy the mail and parcel volume is, weather conditions, time of year (navigating a route in the dark is a whole 'nother animal, especially if street signs and mailbox numbers are scarce/nonexistent, or hard to spot), etc. Even if you know the route by day, it becomes a lot harder when darkness takes over- all your normal points of reference disappear and you're working in a tiny halo of light, often with dirty windows.
TIME AND BUDGET- these constraints are almost constant sources of stress from supervisors/management and are one of your biggest opponents to doing your job safely and effectively.
# ANTIQUATED- it's not any single entity's fault (Unions, Congress, and the USPS all own some of the problem), but working in an outdated system is frustrating. Having a smart phone with Google Maps can be invaluable when trying to find a house, but sometimes it would steer me wrong too.
# Sh&!!Y weather. You might enjoy it in your free time, but when you are under the gun, things can get miserable.
This job drove me to drink, lose drive and lose hope. If you can afford a lower paying job, I would advise it.