That would only make a difference if the boiler is cutting out whilst
there
is still a demand for heat. That's possible with hot water only once the
cylinder reaches 50--70degC, but unlikely with heating as if the rooms are
still below 20deg and the radiator stats are open there should be ample
dumping of heat from the boiler to keep the boiler stat on even at low
settings.

That is only true of an old style non-modulating boiler that has been sized
to the house requirements. A modern modulating boiler is so overpowered
(typically 28kW) that it will very quickly be able to reach the set output
temperature, and bring the radiators up to temperature. Then the boiler stat
will act almost as a power setting for those radiators, long before the room
temperature rises anywhere near the room stat setting.

Christian.