Generally I assume "sauna" will take an hour, or ninety minutes, but the process is pretty much:

1. Have a shower.

2. Sit in the sauna, and throw water on the stones. Stay there for 5-15 minutes, drinking a beer and sometimes listening to music. Depends on the mood what kind of duration I enjoy, and what kind of music I have. If alone music is nice, if with a friend or two then we have silence and conversation instead.

3. Come out and sit on the balcony, to have a little break.

4. If I still feel like it go back to step one, and have a quick shower before going back. Otherwise have a longer shower, and check that the heater is going to shut down soon.