It always surprises me when people control their freezers using beer temp instead of freezer air temp. Water, which is what mostly makes up beer, has one of the highest heat capacities of any material meaning it takes a ton of energy to get it to change its temp. Air has a fairly small heat capacity, it will change temp quickly. If you stick your temp probe that controls your temp controller on your keg/fermenter, your freezer may cool to a temperature well below the temperature of your beer. In a large enough freezer, this could cause your beer to continue cooling past the desired temp then slowly creep back up to your target. By that point the temp in the freezer could be well above your target. While this may reduce cycle times, in theory, your beer temp would be more consistent if you put your probe in the freezer air, midway up and a good distance from the side. Maybe in practice this is wrong though, it seems everyone gravitates towards sticking the probe on the keg or in the fermenter. Personally, I put the controlling probe in the freezer or chamber air then another in/on my wort/beer then set the air temp a smidge above my target temp. Works like a charm with only a little babysitting in the first few days of fermentation.