5
The same evenings most weeks, not a schedule anyone has to keep
The last decision cannot be bought, and it is the reason for the other four. Do not build a roster. Rosters fail the way gym memberships fail: the first missed session becomes evidence the whole thing is not working.
What holds is looser and far more durable. Pick the two evenings already quiet in your week and let those be the sauna evenings, most weeks. Not every week. Most. If one goes, nothing has broken and nothing needs restarting, because there was no streak to lose.
The two of us have been at this since 2021 and are still in ours daily; it is where we slow down and talk, about the business and everything else.
If one goes, nothing has broken and nothing needs restarting, because there was no streak to lose.
Which raises the question couples almost never ask a seller: will we actually use it enough to justify this?
If the honest answer is twice a month, a sauna might not be for you. Twice a month is a nice day out, not five figures in the backyard.
If it is two or three evenings most weeks, the trip and the wait that stopped you at the gym are both gone at home. That is not willpower; it is twenty steps and a room already warm.
If one of you is further along than the other, say so out loud now rather than after the deposit. The five above are a fair test: read them together and see whether both of you can picture a Tuesday evening in that room.
If one cannot, you have your answer and it cost you an afternoon. A sauna two people wanted gets used. A sauna one person was talked into becomes the most expensive place in the house to hang washing.
In the first fortnight, name the evenings out loud, then skip one on purpose so you both learn nothing bad happens. The habit that survives a missed week is the one still running in year three.