Constant PHASE_SUCCESS_INTERVAL_MULTIPLIER 

const PHASE_SUCCESS_INTERVAL_MULTIPLIER: i32 = 10;

A phase that owns a nonempty queue and has not succeeded within this many of its own intervals is running without getting anywhere, which no failure count catches. Never less than its slowest possible iteration plus PHASE_SUCCESS_CALL_MARGIN, or one slow call would look like a wedge.