Thinking about it this isn’t necessarily true in that moving the FOCAL relatively little could yield new things to observe (even microarcseconds). So you wouldn’t need a new FOCAL to measure each new thing. However each FOCAL would be measuring a miniscule bit of space over its lifetime. Which means for each distinct object that isn’t basically a neighbour in angular terms to a FOCAL sent you’d need a new FOCAL probably. Unless our long term energy generation/harvesting and propulsion in deep space significantly improves technology wise.
Thinking about it this isn’t necessarily true in that moving the FOCAL relatively little could yield new things to observe (even microarcseconds). So you wouldn’t need a new FOCAL to measure each new thing. However each FOCAL would be measuring a miniscule bit of space over its lifetime. Which means for each distinct object that isn’t basically a neighbour in angular terms to a FOCAL sent you’d need a new FOCAL probably. Unless our long term energy generation/harvesting and propulsion in deep space significantly improves technology wise.