I am on 84 to 88 ambient only and it works for me so in theory you are correct. If the OP boosts to 84 the hot spot is no longer needed. I was just really curious about the the drop temp suggestion since it goes counter to how I have always thought. I suspect there is possible truth in what Albert said. Immature thermo regulation. And maybe some truth in the same vein with spider as Deborah suggested where their thermoregulation is possibly quirky. Something for me to think about since I will have quite a few spiders hatching next month.