A submittal is the package a precast producer sends to the design team for review and approval before production. It usually carries the shop drawings along with product data, material certifications, and any calculations the specification requires.
One submittal can hold many shop drawings. The design team reviews the package, marks it up, and returns it, and the plant revises and resubmits until the engineer of record stamps it approved. That loop, not the casting, is usually what sets a precast job's schedule.