Mostly simple things: if you have a messaging queue used for logging, and you need to predict the change in its memory footprint given some change in a message

Mostly simple things: if you have a messaging queue used for logging, and you need to predict the change in its memory footprint given some change in a message format before rolling out/testing the format change, just use Little's law. Or you need to determine the smallest number of consumers that you can have online safely to maximize how quickly you can do maintenance without degrading logging.