If it's a password for an account which is only used for automated processing, an expiry period of 6 months is a bit much, especially if the account owner doesn't need to know the password (why is there one anyways). In that case I'd rather opt for a very, very complex password (max out length, use special characters as much as possible, ... something like ]?fb6#Z8"2a[{?(Cl+$? ) that's valid for the next 2 years or so.

Or, even better, if that password is used to remotely connect to a system, drop it altogether and switch to public key authentication with at least 2048 bit keys, those should be save for the next decade or so (just don't use an old Debian to generate them)