It can add a common measure
Harvard can read an SAT or ACT beside students from very different high schools. The score may clarify academic preparation when the local transcript is unfamiliar, but its meaning still depends on course access and performance.
It cannot replace curriculum
The strongest score plan protects demanding coursework and gives Harvard useful evidence without treating testing as the whole academic record. Admissions readers can see whether the student pursued the strongest appropriate sequence; a composite does not manufacture missing preparation.
It can reveal a section imbalance
Harvard reviews the highest ACT composite and permits College Board Score Choice. A section-level plan is therefore more useful than repeatedly chasing a round total without diagnosing the limiting skill.
It cannot predict admission
Harvard publishes section distributions rather than one admission cutoff. The cohort contains admitted students, not a mechanical rule. Students below, inside and above a range can receive different decisions because the application is broader.
It can guide timing
Self-reporting is accepted for review; enrolling students verify official results. The useful final sitting must leave enough time for the route Harvard accepts and for the applicant to confirm that the checklist is complete.
It cannot freeze the policy
For Harvard, current first-year policy describes the verified scope. Testing policies, optional sections and reporting instructions can change; the application term must remain attached to every operational decision.