It would be a waste of time - but if the airport layout would give those people access to the secured area of the airport, and there was no way to channel the c

It would be a waste of time - but if the airport layout would give those people access to the secured area of the airport, and there was no way to channel the connecting passengers separately from the exiting passengers, then you'd pretty much have no choice but to screen every arrival to your security standards. That would just be poor architectural decisions.