I've got a dually trailer, the front bearing might be a little warm, but never hot. The rear bearing/wheels will get hot if I brake a lot. I've got some long downhill stretches and I've learned to slow down and downshift to keep off the brakes. So the rear wheels will be warm when I get to where I'm going but not hot. My trailer is now 11 years old and I've had one bearing seal fail and I tow a lot. I have Vault bearings.
Had bearing buddies on my saltwater boat, had that trailer for 13-14 years, never had a bearing failure and I towed it a lot too and in and out of saltwater every time I launched. Never noticed those bearings getting hot, but didn't have trailer brakes. I got the bearings repacked every two years.
Everything else on the trailer wants to break, I have replaced both leaf springs, turned out they were defective made in China deals, so the trailer company paid for them, but it would've been nice if they had pro-actively issued some kind of recall.
Had a brake line go out, had the hydraulic surge piston deal fail another time, and have replaced the bunks. I've probably forgotten something, but I think that's been it.
Boat and motor (OptiPop) have been fine, replaced the battery charger 6 or 7 years ago. Can't kill that Fortrexx trolling motor. It is getting pretty beat up, but just keeps going.