You're assuming that they all work the same. I've been living in an apartment for the last 15 years where it is indeed mostly on/off. 0-2 = nothing, 3 = in some

You're assuming that they all work the same. I've been living in an apartment for the last 15 years where it is indeed mostly on/off. 0-2 = nothing, 3 = in some rooms the radiator will be warm to the touch but not radiate, 4-5 = warm. It's not the end of the world, we generally have them off until we need to turn them on, and then it's not too warm, and after the winter they're off again for 9 months.