There is absolutely no truth in the idea that having it on all day is more efficient than having it on for a couple of hours in the morning/evening
Really not sure what to think on this one…
I guess “efficient” can be separately defined in terms of “cost efficiency” and “heating efficiency”.
For our house, a couple of hrs am and pm, and the heating never really warms the fabric of the building – the boiler is going full chat for 4-5 hours and not really making a lot of difference…
… it then goes off and the air rapidly cools down again
Whereas full-time on a lower thermostat setting provides a stable and comfortable settting