Ours hasn't been back on since that single hour of boost on the very cold morning a few days ago.
House currently at 20.5 downstairs just from normal living (showers, toaster, people, etc.)
1° outside this morning and the temperature inside had dropped to a less-than-balmy 18.5°, so I put the heating on for an hour and it's back up to 20°.
Before the scoffers scoff, I have small children so keeping the house warmish is fairly important.