A merchant ID is a single processing account. Concentrating all volume in one means one risk review, one reserve decision, or one account limitation can stop the entire business from collecting.
Routing across several MIDs spreads that exposure and gives you somewhere to move volume if a processor tightens its posture. In high-risk-coded categories, which telehealth often is, this is a resilience measure rather than an optimisation.
It also allows routing on performance: different processors have different authorisation rates for different card types and geographies.
A single merchant account limitation in a prescription category can halt collections entirely. Spreading volume is the difference between a bad week and a stopped business.
Multi-MID routing, in practice
PharmaBro supports routing across up to five. Most brands do not need that many early, but having the capability before a processor tightens its posture is the entire point.