Constant DEFAULT_SURB_FLUSH_INTERVAL 

const DEFAULT_SURB_FLUSH_INTERVAL: Duration;

How often SURB round-trip counts reach the network graph.

Much shorter than the protocol counter flush, which is the same order as the recovery window this signal exists to shorten – evidence about a dead relayer sitting unreported for 15 s would defeat the point. Still well inside the graph’s own bucket width, so batching adds no distortion while cutting graph write locks by orders of magnitude.