Scaling down galaxy app: select specific container?


Hi, my use case requires “protecting” a specific container in case of a horizontal scale down (reduction of the number of containers). My experiments showed that pressing the down arrow button picks the container with the least resource usage. However there seems to be a time frame of about 5-10 seconds where I can kill a specific instance and that instance will instead be used to achieve the scale down. I’m wondering
a) is this behavior guaranteed?
b) is this the only way to achieve my goal (I’m worried that I might not be able to select the right instance quick enough)?

FYI: I’m trying to protect some containers because they’re running a long poll on a third party service which shouldn’t be interrupted as long as it can be avoided