Thermostatic Radiator Valves - on all radiators?

[Possom]

Is it best to have thermostatic radiator valves on all radiators in a house, or are these only placed on radiators in certain rooms? If so, which rooms?

Thanks!

 

[Tipper]

All radiators...except in the room where the room thermostat is located as the room stat and the radiator stat would conflict with each other