How often do y'all change out fluids other than engine oil?

Yes, they need to me changed, the manufacture recommendations are minimum you should follow. Last night on my way back from Bakersfield on my round 2, I pushed a Dodge 4x4 350 crew cab off onto the should in the middle of the steep part of the climb east bound toward Tehachapi, truck showed 230K, pin-hole in the lower radiator hose, I cut it inserted a piece of galvanized pipe (I found on the shoulder, don't know how it got there but it worked) added a couple of hose clamps out of my tool box, topped them off with water, and sent them back down the hill to Bakersfield, Don't think there's lot of options going east at 22:00 hours. He told me Dodge told him not to worry about the cooling system , he had just had it serviced. He's now on board with the yearly replacement of hoses and belts......
Yes they need to be changed..