I also have hive heaters and I also leave them on all of the time, but having said that, I work from home and have fantastic smoke alarms! I'm not sure if I would do that if I was salon based, and I'm not sure how happy my house insurance would be if something did go wrong.
I'm not keen on blasting my wax on high first thing of a morning then letting it cool, every time I've tried this I feel there are issues with the consistency and the wax snapping. I know if I top my pots up at night and leave them on overnight at the right temp my wax is perfect with no issues.