Sauna for recovery is the reason a lot of the cabins in this index get bought, and the evidence behind it is better than the detox claims and weaker than the marketing. Heat does something useful between hard sessions. What it does is not the same as what cold does, and the two are often sold as interchangeable when they are not.
What heat plausibly does
Heat raises heart rate and dilates blood vessels much as light exercise does, increasing blood flow to muscle, and most people report feeling looser and sleeping better afterwards. Better sleep alone is a real recovery mechanism. What is not established is a measurable acceleration of repair, and anyone promising one is ahead of the data.
Heat and cold do different things
Cold immersion reliably reduces soreness and, immediately after resistance training, appears to blunt some adaptation. Heat does not carry that finding and has been studied as a possible adaptation aid rather than a brake. Practically: if you lift, heat is the safer thing to do straight after a session and cold is the thing to move away from it.
Fitting it around training
Most people who use a cabin for recovery settle on a session after training or in the evening of a hard day, moderate rather than maximal, with real hydration around it. A sauna is a cardiovascular load, so a very hot long session on top of a very hard session is adding stress at the moment you were trying to remove it.
The contrast question
Alternating heat and cold feels excellent and is the format most home setups end up in. The evidence for contrast therapy outperforming either alone is thin, so do it because you enjoy it rather than because a protocol promises something. If strength adaptation matters, keep the cold end away from the hours right after lifting.
Questions people ask about sauna for recovery
Is a sauna better than an ice bath for recovery?
They do different things. Cold reliably reduces soreness and can blunt adaptation right after lifting; heat carries no such finding and suits the hours after a session better.
How soon after training?
Any time that day, moderate rather than maximal, with proper hydration. A very hot long session on top of a very hard one is more stress, not less.
Does contrast therapy work better?
The evidence for contrast beating either alone is thin. Do it because you like it, and keep the cold end away from just after lifting.