The whole 15-20min, keep it lower. But It has a few times told me to cool it down.
I find if I wrap in a shirt/towel to use as timer it's helps just enough and no prob. If I scroll on it though I get the warnings š³
If I'm listening only I just put on the floor, cold enough.
Sauna is a place I'm actually not listening to something for once š¤·š