I'm wondering how regular users of hot tubs, kept outdoors in winter up North, manage their heat/cool down cycle most efficiently. Our tub is new, a basic model but spray insulated to current industry standards (or to Nordic's standards) with a nice fitting cover. My wife and I soak most days, usually afternoon/eve. Thereafter I've been setting the temp to 85 and let it fall till next use. Typically the temp has fallen all the way to 85 deg by the next day (especially this frigid winter) implying it may have demanded some heat to maintain, or will before our next use preheat. I could set it lower (needing a longer preheat prior but less interim heat). Or I could set it higher to avoid the longer preheat, but with an obvious tradeoff in interim heating. Is there an ideal breakpoint, the goal being the least use of electricity? What about when the outdoor temps moderate?