I usually keep my thermostat at 23C (73F), once it drops to 22C it heats up again to 23. THe problem is that I live in a one-room flat, just under the roof, all walls are outside walls and to make things worse, it is very poorly insulated.
So in the summer, as soon as the temperature rises for just a day or two, it immediately heats up to around 30C (85F) and stays like that for weeks... and of course no A/C...
In contrast, right now, I usually turn of heating when I go to bed, which is around 4:30AM, and the inside temp is close to 23(73). When I get up at 8:30 it is usually around 19C (66F) and remember that it is still not that cold outside, only around freezing point. And I leave it off and go to work. I can watch the temp when Im at work on my station, by 3PM Im usually down to 15C (59F)! It really changes very quickly. At that point the heating sets off again and maintains the T around this until about 9PM, which is when I have it set to start heating at maximum and by the time I get home around 11:30PM or midnight, it is back to 23 (73).
But winter is obviously not such a bit problem, if Im cold I just turn up the thermostat... if it is too hot, however, there is not much you can do... and last year we had an extreme heat wave in July/August and I remember the temperature in my flat did not drop below 32C (90F) for over 2 weeks! Including night-time! And in my office it was slightly better but I also dont have A/C there...