…I wouldn’t worry too much about it for a couple of reasons. Most commercial roasting is done in quite large batches compared to the beans pulled out by a trier. Even a 5 kg. machine with a 3 kg. batch is quite large compared to the couple of grams that would fall into the trier. We’re talking degree changes here that are so minor, they are (in my opinion, don’t send me hate mail…) insignificant. Secondly, when the beans in the trier go back in the drum or ‘bed’ of beans, they’re immediately dispersed and the temperature fluctuation would be nearly undetectable. I wouldn’t get caught up in the minutia here, it’s like changing the temperature on your espresso machine 0.2 degrees and expecting game changing results…
Also, a number of roasters are using advanced software to replicate roast profiles on a consistent basis. This might take away the need to use a trier constantly as you’ve eliminated some of the variables and have a reasonable expectation of the key events of any given roast (1C, RoR, DTR, etc.) based on previous and historical data.
I suppose in home roasting (think Behmor…), if you were to constantly open the door, this would almost certainly have a negative impact on your roast due to the smaller batch size and much smaller volume of hot air and overall mass of the roaster (plastic, aluminium, sheet steel vs. cast iron).