Logic question - XDIM_MEMBERSET vs WHEN

Greetings,

I've taken on the Admin role for an existing budgeting application that has budgeting calcs built into the default logic. I need to start loading strat plan data to its own category through an input schedule. All the logic is scoped by XDIM_MEMBERSET CATEGORY=BUDGET. Will the default logic still run for the existing Budget data if I send data through a schedule to a category of STRATPLAN? Is there any overhead involved, scanning of records, etc? Would a WHEN CATEGORY IS BUDGET be needed? Basically, when there is logic in default that should only be run for a certain category what is the appropriate method to scope that logic so that it does nothing at all when data of another category is sent to BPC?

Regards

Edward