If I remember correctly, the card says your next Strike gets a 60/90% damage bonus if you haven't fired your weapon in the last 6 seconds. I always thought this meant that you get only one Strike with the bonus damage, and then you have to wait another 6 seconds without firing your weapon before you get the damage bonus again.
However, from what I've tested, it seems that as long as you don't fire your weapon, all your Strikes get the damage bonus. I'm not quite sure if this is a bug or intended.