Most medical schools review applications and extend interview invitations continuously as complete applications come in, rather than waiting for one fixed deadline to evaluate everyone at once. By the time a late application is fully read, many interview slots — and sometimes entire seats — are already filled.
Submitting within the first few weeks after AMCAS opens is a real, measurable advantage under this system. "Late" in practice usually means submitting after mid-July, or returning secondaries slowly over many weeks instead of within that two-week window. An early, genuinely polished application consistently outperforms a late, theoretically perfect one, which is exactly why getting application-ready ahead of the May opening is worth planning for months in advance rather than scrambling in June.