I think most here would agree that two or more machine made marbles manufactured one after another is a run. Subjectively speaking, I say it remains a run until one or more variables alter the appearance of the marbles coming off the rollers to the point where the human eye can detect a consistent difference.
So if JABO makes 1 million clear industrial marbles, it's a run insofar as they all look the same to us. But if midway in the process Joe's watch slips off into a glass tank, then there will be a brief "Joe's Timex" run.
If Akro Agate was able to precisely control all of the variables of the manufacturing process, especially the variables in big quantities of raw materials used in the glass recipes, then theoretically they could have produced Sparklers a year apart but which to a collector's eye look like the same "run" (or batch). But I consider that a very tall order given the complexities of a Sparkler marble. Think of just some of the variables that could alter one or more aspects of a marble's appearance: temperature, equipment wear and maintenance, employee skill and error, and especially those mass quantities of raw ingredients and the recipes. Think of those variables influencing the look of a Sparkler. It sure as heck ain't no Prize Name.