With todays LCC schedules demanding ever tighter turnarounds, the fact is that many crew MUST accomplish their tasks in short time. The risk of making a mistake is increased not only because of rushed tasks, but that the many figures they deal with can be transposed from the previous sector. Something I have seen often.
I became increasingly frustrated that I could not go a single week without making at least one stupid mistake, however much I tried not to. What I resolved to do was have my own way of systematically checking my work. At times of high stress (delays, confrontations, lack of sleep, just having had my butt chewed by a pilot/mngr/pap/ramp, etc, I would turn double checks into triple checks and force myself to do them slower and more deliberately concentrating on the big stuff first like getting the loadsheet 100% accurate. Eventually, I realised that the trick wasn't to make no mistakes at all, it was to ensure that every mistake was spotted before it reached the flight deck, since they would have far more to consider and deal with themselves. My job was to make their job easier, since theirs is most definitely the harder, but if I couldn't do that, then at least I should not make their job harder or distract from their tasks.
It could be argued that the fuelling error did contribute in some way to them overlooking the procedures that would have identified the bug-card error. This was another lesson I learnt; when things start to go wrong and you are deflected from your usual procedure, then check everything else again.
I'm very happy that this mistake did not harm any individual, yet can still add to other pilots' wisdom when faced with similar circumstances.