Would that 34% come from fear and stress? People at office feel the pressure more and work above their means and then take holidays when they are completely bur

Would that 34% come from fear and stress? People at office feel the pressure more and work above their means and then take holidays when they are completely burned out to recover instead of enjoying it. 66% is probably your real baseline level of productivity and something to learn from. If you are their superior they may not even be your friends, but just pretend they are out of fear of being fired or treated unfavourably.