As already written, it depends on whether you brake or not. If you drive 100 miles on the freeway and don't brake, the brakes aren't even warm to the touch. If you're driving normally in city traffic, the brakes are warm and if you're driving downhill with a trailer they get hot. If they are so hot, after a normal ride without braking, i.e. country road, or highway, that you can hardly touch them, then something is wrong and especially if one wheel, or two differ significantly from the others in temperature.
As well you can carjack the car and try if the wheel is free turning, when you're in neutral.