I personally shake it before using Thunder, but according to the wife, who knows far more about this stuff than I do, the essential oils in a carrier creates a perfect suspension, so it needs no further shaking.
But I’m paranoid… I once dumped a little Cinnamon Essential Oil in a hot bath to soothe a sprained muscle or something, but didn’t know that I had to add something to make the oil mix with the water. Long story short, I sat on a bubble of the pure oil, didn’t notice the irritation because the bath was so hot, and ended up with a nasty chemical burn on my ass cheek. :D So now, I’ve got it stuck in my head that if I don’t shake the EVO oil, I might get some concentrated Rosemary on my skin which would burn worse than the Cinnamon.
Also, anybody using non-essential oils in the EVO, like adding DMSO or ground Niacin, I’d shake just to be on the safe side.