Start with the consequential failure modes. Which mistake would make the result unusable, unsafe, or expensive to undo?
Choose a check that would detect each concrete risk. For a calculation, independently recompute a representative result. For persistence, confirm that a saved item can be read back. For a migration, test constraints with realistic data. For a document, inspect its rendered output.
Stop optional checks when the remaining uncertainty is acceptable for the task and required gates have passed. Explain untested limitations honestly.
This is a suggested workflow. Add examples where a targeted check found something that a broad test suite missed.