Zero shot you'd make it an hour in a proper sauna for an hour. People have this idea that saunas are always enjoyable. I sauna daily, and its nice up to a point. For me thats like 10-12mins in. From then on, its tough.

When it doesn't feel enjoyable anymore, you're supposed to get out of the sauna and cool down - preferably in a lake. Then repeat as many times as you like.

I go for 15 min sessions at 90 Celsius and the first 10 mins are ok, the last 5 are tough, like I have to control my breath to hang in there

Huh what? I can easily sit in a sauna for an hour without breaks as long as it has some type of ventilation.

Smoke saunas a bit less, electric or wood stove saunas no issue. It's nice to take a breather once in a while but I'd honestly have no issues sitting in a 80-90 deg sauna for an hour as long as I have enough to drink with me.

One time I sat in the sauna for six hours with a few breaks between with a group of friends shooting the shit. I had a headache the next morning but I blame it on the Jallu and not the sauna.

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?

You are clearly not Finn (/s)