Simultaneous lands entering
Cards with effects like Circuitous Route cause the lands to enter at the same time. So only the scute swarms currently on the battlefield when the effect is played trigger and create copies for each land coming into play
If you have 2 scutes have 6 lands and play Circuitous Route, both scutes will trigger 2 times and you end with 6 scute swarm and 8 lands.
