I dunno. I threw my last batch into a big plastic tote, directly from the smoker, and just let them rest in the garage at around 45deg F till the next day. Too lazy (it was late when the temp hit 160) to ice them etc. Everyone likes them.
But did some 17mm sticks that had tough casings a couple batches ago. People were troubled a little. Not up to my usual product. I need to keep experimenting. I am certain that there are a bazillion ways to do this, but also a lot of ways to screw it up. We all need to find out process.
I do think its not a good idea to mix sizes in the same batch. My 17mm fail (not really, were still quite edible) was part of a mixed batch. So they got over cooked while waiting for the 19mm to get to temp.