It is wasteful of energy to keep a house warm when there is no-one in it. Modern boilers are usually sized to heat a house from cold quite easily and quickly, then modulate down (reduce the flame) for quietness and economy. This will not work though if the radiators are too small to deliver enough heat.
With modern well-insulated houses and programmable thermostats, you can set the temperature according to time of day and day of week.
For example, ours goes to 15C overnight. Usually the house will not get as cold as that, so the heating stays off. However during a very cold night, if the house does get down that far, the heating will come on for long enough to raise it again. Then go off. You probably wouldn't even notice it had come on.
It turns back up to 20C half an hour before getting-up time. During the day (weekends when there are people at home) it stays at 18C, because you feel comfortable when active, especially if the sun is out, but increases again in the evening when people are sitting around and it's dark.
On work days it changes to 15C during the day when the house is empty, but it might just as well be turned off because it is very rare for the house to get so cold after having been warm in the morning. I really noticed the difference when CWI was installed, if I was working locally and came back at lunchtime the house was not cold even in winter.
If the house is empty for a winter holiday, it is set to 12C day and night (as required by house insurers) and returns to normal program on the date of our scheduled return.
If anyone cares, you can put a programmable stat on the wall and connect it to the wires from your old dial-type thermostat. It will have a battery to keep its own clock correct.