If I'm treating a crowded upper arch vs both arches with crowding that includes impacted L7s, both will take me 2-3x as much chair time as if I'm doing just the upper. But one arch of crowding and two is not too different.

I charge based on complexity and duration. I don't think it's fair to charge someone more just cause their kid's case is simple compared to someone where I'm gonna be struggling with mechanics or compliance for a lot longer.