How Arc differs from test planning
Test planning is the software: spec to a defensible plan. Arc is the campaign: overview, parallel institutes, logistics, one report. Both share the same coverage logic. Accredited test houses run the tests. The certificate comes from the partner, not from Cevelar.
Calendar time follows the longest track, not the sum of every single test. That is why parallel, not sequential. The starting point remains a clean plan: validation planning.