I've long felt that
Usage of "open enrollment" is strange.
It's used like a foreign phrase.
https://www.healthcare.gov/quick-guide/dates-and-deadlines/
November 1, 2016: Open Enrollment started — first day to enroll, re-enroll, or change a 2017 insurance plan through the Health Insurance Marketplace.
https://en.wikipedia.org/wiki/Annual_enrollment
During open enrollment anyone who wants to purchase insurance through the public exchange has the opportunity to do so despite circumstances, such as health or age. Outside of open enrollment it can be difficult to obtain insurance, either public or private, unless circumstances dictate.[1]