What's the most effective way to mix a jar of natural peanut butter?
I've done this with almond butter, and I imagine it would work for peanut butter as well. The secret is to buy it a month or so before you need it, and then store it upside down for a week, so the oil traverses all the way through the jar and its contents, then turn it right way up for another week, and repeat again in each direction. Each trip through the jar mixes the oil with the solids a little more, and it's fairly homogeneous after four turns.
I was going to post something like this, except it's not always necessary to even turn more than once. I just leave them upside down and don't have to think about it. You'll end up with extra oil on the bottom, which is only a problem if the consistency is too thick without the extra oil getting integrated.
True, it works with less turning around, but doing it a few times really makes sure the oil is evenly distributed. Four may be overkill/ritual - there may be some brand dependency.