Only the first two times. The first time was mid-March (‘16) and it was 30-ish and snowing overnight. The babies were 2-week old ducks and 3-week-old chicks. They slept at the other side of the coop 6’ from the heat lamp, and it was 3’ up. After the second night (heat overnight only) of checking several times overnight, and never hearing a peep or seeing them near the lamp, I kept it unplugged.
The next time, it was probably November. They were one week, and I used the lamp for a week. The third or fourth night, they didn’t sleep near it. I raised it, and raised it. They were fine.
Now for the one fail. I think it was last spring (‘19) that I had one chick crushed, and one chick freeze within an hour. I was using a prefabricated (as in garbage) coop, and they were likely still weak from the conditions at the feed store (dead chicks in the feed store bibs, and two chicks died the first day, in the house!). I doubt that would ever happen again.