I personally don't really use it.
I have used it in the past a few times to induce a greater GH response to training (I had a sauna in a gym I worked at and would go in for 5 minutes in between exercises).
But the results are minimal, if there are any, on fat loss. Furthermore they increase the risk of dehydration and doing just a little bit too much will jack up cortisol.
As for recovery, my view on recovery methods like sauna, ice baths, contrast showers, massages is that your body adapts to them. And when it is adapted the increase in recovery stops. So it is better left for short periods of time where you need to increase recovery capacities (shock week, deloading, peaking for a competition).