Acu_Rite thermometer

Just wondering if those of you out there using them, use them in every tub or every row of your rack or 1 per rack? I am thinking of picking some up to try out.

I am sure most people who have racks have a temp gun so they can check the temps of all the tubs with one device.

You could get one for each tub or for each rack, but I think that might get a little pricey after a while.