I used to be happy with it set to 17/18°C, and very rarely had it at 19/20°C, but my arthritis has got worse and I really feel the cold now, so I generally keep the downstairs at 20°C during the day, although the house is often naturally at that temperature, without the need for the heating to come on.
If I'm not moving about much, and I'm home most of the day, I may turn it up to 22/23°C and will turn it off when it reaches that temp, but it really depends. I did have it set for 20°C to come on at:
7am for 90 mins
then again at 12noon for an hour
then again at 4pm until 9pm.
We have 2 zones, so the upstairs is kept at 16/17°C during the day, although tbf, it hasn't actually come on yet as it's always around 18/19°C without the heating being on. The upstairs is only set to come on at 20°C for 90 mins from 6am, so that it's warm when people get up. It's then off all day and is set to come on again at 7pm for 2hrs.
This is set to 21°C. So far, it's often warm enough anyway and the heating doesn't actually come on.
Both zones are set to 16°C overnight (from 11pm to 6am), and if no one is home the heating won't come on and stays at the eco setting of 15°C. Generally though (apart from my bedroom, which goes down to 14/15°C), the house doesn't really seem to drop below 17°C so far and it's 2°C outside here today.
I've just turned my schedules off though as I thought I'd give the auto schedule a try. This allows the thermostat to create it's own schedule according to how we use it.
If this works out cheaper, I'll stick with it.
I used to spend roughly £1200 on gas and electric for a family of 4 living in a 70s semi with about 150m2 living space (4yrs ago).
Just moved into a much newer detached property with about 250m2 living space and a lot more glass. It has partial underfloor heating as well as the 2 zoned areas. Looking at my heating history, the heating has been on for an average of 4hrs/day over the last month (includes the Christmas holidays), and according to my smart meter I'm spending about £7/day on gas and electric, although that does include charging a car.
Don't know if that's good or bad though (feels really high to me).