I do remember in the 60's having an inferred heater, it had 4 bars, as switching on/off does not work, as soon as you switch it off you feel cold, so output was adjusted by how many bars were switched on.
Even small bathroom heaters tended to have two elements.
Normally we use inferred heating as part of a larger package, I used it for years, it was called tungsten lighting, the thermostat was set to 18°C air temperature, we was ample during the day when moving around, then in the evening we switched on the lights so got inferred heating from the lights which resulted in room feeling as if at 21°C. When we swapped to LED lighting we also had to change the thermostat to a programmable type so temperature was raised in the evening, which of cause resulted in air changes costing more energy, but saving money as used gas for heating.
I have looked at the idea of controlling inferred heating a few times, but only method is to split the heaters into sections, so more or less sections activated, yes the inferred does heat the items in the room, and then they heat the room, but the difference felt between off and on is too great to get automated control.
We see this outside, the sun goes behind a cloud and we feel cold, but the metal of the car can still be too hot to touch. But inferred heating passes through glass, so during the day they need aiming so they do not shine at windows. But only way to control is when combined with other forms of heating, so we keep air to say 16°C and we know the inferred makes that feel like 22°C but it is the back ground heat we control, not the inferred.
