The fastest MVP data model is often the most expensive later: free-text statuses, JSON blobs where relations belong, user tables that conflate buyers and sellers. Each shortcut shows up when you add payouts, reporting, or multi-tenant admin.
We model the entities that will not change — users, listings, orders, payments — with normal forms, foreign keys, and migrations from week one. Flexible fields live in metadata columns or feature flags, not as a substitute for structure.
Reporting is a common surprise. Founders want dashboards at month three. If events were never logged and orders were overwritten instead of state-machined, you rebuild history from scratch. Lightweight event tables or audit columns cost little upfront.
Eight weeks is short for features, not for foundations. The schema should survive your first pricing change, your first B2B contract, and your first AI feature that needs historical context.