The story
A university site is not one site. It is a decade of departments, each with its own pages, news posts, staff profiles and PDF handbooks, all on one WordPress install that nobody has fully audited since it was built.
For most of the year that is fine, because most of it is barely visited. Then admissions closes, or results are published, and thousands of people arrive within an hour looking for the same handful of pages — and the install that was comfortable at ten visitors a minute meets a thousand.
Almost all of that content is static: it has not changed in months and will not change today. Served as cached HTML and prewarmed before the deadline, the spike becomes a non-event, and the only pages doing real work are the ones that genuinely need to.