How often do you search for BIOS updates for your computers?

It's part of my monthly maintenance -- though, in the last year I've probably only had one update arrive. It only takes a few minutes a month to make sure stuff stays up to date, and it's well worth it.

If it ain't broke, don't fix it.
I have had too many crashes due to updates to go looking for them.

If there's a known security risk associated with my version of BIOS, I'll update. Otherwise I don't tend to worry about it (an exception might be made to this in the event of a particularly annoying bug but, so far, never happened to me). As such, I'd say rarely.