Logic behind badge assignment to user based on certain amount of activity done by user.

Yes I dot agree that lithium must be saving the data in DB, but count
of that activity also is greying stored. I mean when user creates
another message , does lithium increment the count and store the
aggregated count value for number messages done by user so far and
keep on increasing whenever user creates new message. Or lithium every
time during run time calculates the count of messages when user
creates new message and assign a badge .