I generally make it about 30 seconds in a sauna (I rarely even bother trying when I have access). Should I tough it out for 10-12 like you? Should you be toughing it out for the full hour I suggested (a random time I pulled out of my head)? Or is this all nonsense and I'm just fine ignoring the whole thing?

30 seconds? What kind of torture room of a sauna are you going in?

IMHO. 10-20 mins is good enough. I wouldn't try to stay for an hour.

If 10mins feels too much, do less.