No, I really haven't followed all the update patterns. I take a look at my logs every once in a while to see what the current state is and see this:

12/29/2008 7:51:20 PM Kernel Virus signature database successfully updated to version 3722 (20081229).
12/27/2008 11:59:58 PM Kernel Statistical information was sent to ESET.
12/27/2008 11:59:45 PM Kernel Statistical information was sent to ESET.
12/27/2008 11:59:33 PM Kernel Virus signature database successfully updated to version 3719 (20081227).
12/26/2008 12:38:22 PM Kernel Virus signature database successfully updated to version 3718 (20081226).
12/25/2008 10:19:34 PM Kernel Statistical information was sent to ESET.
12/25/2008 10:19:33 PM Kernel Statistical information was sent to ESET.
12/25/2008 10:19:32 PM Kernel Statistical information was sent to ESET.
12/25/2008 10:19:31 PM Kernel Virus signature database successfully updated to version 3717 (20081225).

So I guess I either had the machine off on the 28th (which I know I did) and then missed 3720 and 3721. There's probably a reason for how it updates. But it updates itself in the background, keeps track of what it is doing and is pretty quick and unobtrusive. Seems to take about 15MB of system resources (which is really nothing).