Why does enrollment close?
The countdown shows the time left available for you to join. Once the timer is done, enrollment will be shut down.
Having an open/close enrollment makes it possible to manage the workload for customer support, especially since I'm personally inviting students to the Notion workspace as guests (they don't have an API yet).
It also allows me to provide the best support for new students getting started and going through the course. There are inevitable questions that pop up and I like being able to make it as smooth as possible to get going.
The open/closed period encourages cohort waves so more students are on the same page at the same time. You definitely _can_ do everything in your own time, but sometimes it's more fun to do it with people.
Lastly, open/closed enrollment also allows the Design Advisors to be more involved with each new enrollment period. Giving feedback, answering questions, etc.