There is no need to ever update the bios unless:
There is an issue that you have that is specifically addressed in a new bios.
A new feature(like added CPU support) is added to the new bios that you need.
When manufacturers release a new bios, they also release a guide that lists what was fixed and added
There is a risk when updating the bios. I've bricked a couple of MB's myself, and there are many posts about issues with bios updates.