Constant FLUSHES_BETWEEN_REPLANS 

const FLUSHES_BETWEEN_REPLANS: u32 = 8;

Flushes a destination must wait before it can be re-planned again.

Silence accrues per pair of legs, but re-planning acts on the destination, and a destination carries several pairs at once. Re-arming each pair individually therefore still allows one destination to be re-planned every couple of seconds – faster than a freshly chosen return path can be established and start delivering, so each re-plan destroys the candidate the previous one selected. Measured with the invalidation finally reaching the cache: fifteen re-plans during a thirty-second healthy baseline, which collapsed it from 100% to 0.1% arrival.

Long enough for a new path to prove itself (it needs SILENT_FLUSHES_BEFORE_DEGRADED flushes just to be judged), short enough to retry twice inside the recovery budget.