My first RV, a 2003 Horizon Itasca (same as Journey) got a plugged air dryer after 6 years. (original owner ran it three winters in New England winters, ugly wet roads) It was dripping badly, air system intermittent problems, etc. Got it to a Freightliner shop, they couldn't get parts for it (too old they said). Ended up getting a new unit. It was tucked up behind the rear axle, driver's side, canister looked like a gallon paint can, size wise).
My current RV, I had the air dryer serviced at 6 years, no problems, just thought it might be a good idea. Freightliner said they replaced the filter and serviced the mechanism, but all looked great, didn't really need servicing at all. I don't drive much in wet weather, at all. So your needs may vary.
2010 Journey 39n - 2017 Jeep Cherokee Trailhawk - this our 12th year living aboard, traveling in Texas for the winter, still avoiding the virus along the way!