One of the Golden Rules is "one FD off, then sw both off"
As far as I know that's only a golden rule on the Airbus, not on Boeings.. reason being (if memory serves) on the bus if the A/THR is still engaged it will be doing what the remaining FMA says it is doing, and the FD-less pilot (assuming PF) might not get the thrust s/he is expecting. But current bus drivers are more qualified to comment... it's been many years.
MY only golden FD rule is... look through the bloody things!
