this is handled automatically by each and every worker every 5 cycles (with default heartbeat of 3 seconds, it's 15 seconds).
You can "force" the job that is done every 5 cycles setting "PICK" as a status on the workers.
That being said, if it doesn't add up in your environment you'd better triplecheck if there are exceptions going around: what you're experiencing should last 15 seconds AT THE MOST.