It doesn't have anything to do with show elements. The launches allow the coaster to be divided into sections. Basically, if an emergency stop was performed, the launch sections would act to slow each train to a halt. That's how, under absolutely ideal, perfect conditions you could have that many trains on the track at once. But given the short distance between each launch and the existence of a few still show scenes that would wreck the timing, it's highly, highly unlikely that there would be 8 at once.
