Examples when to flash the BIOS usually are:
1. New CPU was released
2. Memory compatibility issues + new RAM models are released
3. Remember when the new 2+TB HDD have been released? New BIOS was needed.
4. New hardware support added.
5. Or if u can benefit from changes in the change log.
BIOS updates are always risky for various reasons.
Especially when wrong BIOS is used.