Weighted shortest job first is applied to backlogs to identify what?

Weighted Shortest Job First (WSJF) is a prioritization model used to sequence work for maximum economic benefit. In SAFe, WSJF is estimated as the relative cost of delay divided by the relative job duration. In a flow-based system, priorities must be continuously updated to provide the best economic outcomes. In other words, job sequencing produces the best results rather than prioritization based on a theoretical return on investment for each job. To that end, SAFe applies WSJF to prioritize backlogs. Backlogs are continuously prioritized based on a WSJF algorithm that uses relative user and business value, time criticality, risk reduction and/or opportunity enablement, and job size. WSJF also conveniently and automatically ignores sunk costs, a fundamental principle of Lean economics