My maximum what I have been in sauna is ~95 degrees celcius, on my friend's sauna. On other saunas I haven't been on that high temperatures, 80 maybe. How "wet" the air is in the sauna has a big meaning on how hot it feels, on dryer saunas it feels more hot. But also if it is too wet I get bored and frustrated because I cant get high "peak" enough after throwing water to the stove.
Usually the first time on sauna is just getting it warmer enough by "beating" the water as much as it is needed, whit fast pace. It usually takes ~10 minutes, after that a short cold shower or even better a swim on the lake. Then some 5 to 10 minutes "sessions" and always something cold between.
Usually it is 30 to 40 minutes overall, but on good, a bit drunken days I have been there like 3 hours overall...
I'm not usually a special "hot master" with my friends, but when I get a bit taste of alcohol (best is a bit of vodka, or something with 40%) I'm usually the last sitting on the sauna beating more water to the stove until I ran out of the water.
Cold beer after sauna is the best.
Your sauna session isn't a success if your skin is not red all over.
I love sauna, but I think that the best moment and the real meaning is the über relaxed feeling afterwards.