Most features have a lead time before Requirements, Architecture and Epic Backlog is available to the scrum team. There is a misconception that these Sprint zero, or planning Sprints are the way of Scrum but are actually waterfall methods. Also this approach doesn’t essentially lead to team empowerment of the product backlog during sprint execution.
Blitz – brings in a time boxed intense collaborative approach with involved stakeholders and scrum team agreeing on requirements, architecture, acceptance criteria and product backlog priorities. This is part of the Scrum execution cycle rather than a Sprint 0/Planning exercise.This brings in a parallel and lean approach to expedite a refined development ready product backlog.
This is an approach executed at various projects to reduce the feature delivery timeline and understand/minimize the unknowns.