Hello Lyle,
You will get a number of responses to your question. The preliminary caveat should be YMMV (Your Milage may vary).
I’ve run as few as 8,000 miles and as many as 17,000 miles. I pull the wheels down, check brake wear, examine magnets and drums, clean and service the bearings and spindles, reinstall with new inner seals each early spring, and adjust the brakes. We don’t have self adjusting brakes. This is before the camping season starts for us. Usually in March. I rotate the tires at 8,000 miles including the spare in rotation.
I do this work myself because I like to see the condition of things for myself, I’ve had this type of regimen for other trailers I’ve owned for 60 years, have the tools and a good inside shop to perform the work and finally, I’m not adverse to doing the work myself to save some money. My rotation pattern is: spare to right rear, RR to RF. RF to LF, LF to LR and LF to Spare. I torque the lug nuts in three steps. 35, 65 and 95 ft lbs and recheck the torque at between 50 and 125 miles ( usually our first trip first stop is in that range whether we stay one night or more).
Hope this helps.
Iowa Dave