Using the separate upper/lower setting allows you to save time and money by creating the minimum number of models needed for your treatment plan.
Checking the Separate Computation of Stages for Upper/Lower box splits the timeline to show a different number of stages, based on how much movement is required. If only a single arch needs aligners, the stages have a half-filled in circle corresponding to that arch.
When not checking Separate Computation of Stages for Upper/Lower, the software exports an equal number of stages for both arches. The arch with fewer stages has its movement slowed down to match the number of stages for the upper. In situations with Goals, the software generates non-active stages for Goals that do not have any movement on that arch.
