I would second that, I put mine on the edge to keep an eye on things, but will check the middle as things get closer, eitherway though you shouldnt have a significant temperture change in a normal sized pot, maybe in something more industrial sized, but even then the idea is an even temp through out so you shouldnt be at a point where you have a big temp difference throughout, couple degrees I doubt in the whole scheme of things will make any difference you would have to be able to procees and finish PRETTY fast for it not to still be able to even out the temp through out.