[stcredzero]

If cosmic things had millennial checkups, they'd be cosmic-scale in their hypochondria. That would be like me getting a checkup every second.

[lioeters]

I wanted to find out the unit of time of "every billion years" - first thought was "billennial".

Apparently, a millenium is otherwise known as a kiloannum; a megaannum is a million years, and a gigaannum is a billion.

So, a reasonable universe should be getting gigaannual checkups.