If you're at 24 hours no and you're only shy of that at 20...so really that doesn't leave a lot of cool down time. I think it's preferable to have your nights even just a couple degrees cooler, do you have a fan going? No matter what if your lights are off even though the thermometer might not change, your leaf surface temp will change, so that should hopefully be enough. Once you're in flowering though you should see if you can change that even a little.
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