Benchmarks are figures of merit for the characteristics of projects or processes that are generally deemed as being successful. The relevancy of those benchmarks to your project depends on the degree to which your project has common or similar objectives, customers, deliverables, and processes. For Project Management benchmarking, a PMO would be a good place to retain, update and share that knowledge. The Project Manager should be the one who determines the benchmark relevancy to the project and the one who uses that information to set objectives, establish metrics and lay out the plan and scedule.