I am testing ways to improve RPM and keep going back and forth between broad targeting and tighter filters.

The campaign is focused mostly on US traffic with an emphasis on mobile users.

Part of me wants more control from day one, but part of me thinks I should let the campaign gather broader data before trimming too much.

1. Launch with enough volume to collect meaningful data
2. Cut obvious losers early
3. Avoid changing too many variables at once

How do you decide when a targeting segment deserves its own campaign instead of staying inside a broader test?