Schedule is the product
On a production build, the roof is not a standalone trade — it is a gate. Framing and sheathing finish, the roof dries in, and only then can mechanical, electrical, and plumbing rough-in proceed with any protection over their work, insulation follow, and drywall be scheduled. A roofer who misses dry-in by four days does not cost you four days of roofing, they cost you four days on every trade stacked behind it, times however many lots are moving at once.
That is why sequencing gets set against your framing calendar rather than against ours: dry-in immediately behind sheathing and cornice, then final roof after the roof penetrations are set. Plumbing vents, range and dryer terminations, bath fan exhausts, and HVAC flues all pass through the deck, and every one of them set after the final roof is a hole cut in a finished system.
