Our team of 5 (including supervisor) were asked by higher management to stay late after work to carry out a task that isn't part of our normal duties, but was necessary for the company as a whole due to the actual team responsible having got behind for some reason and left work without completing it - it was needed for the next day.
Say there were 100 "things" (each of an equal level of difficulty) to be processed as part of this task e.g. forms to be entered on to an electronic system.
We split it into 5 * 20 things (as there were 5 people) so each of us were given a batch of 20 things to be entered. There was an implicit understanding that we would leave work once they were complete.
I set to work on my batch of 20 items and was finished in about 45 minutes. The others were taking much longer due to a combination of: 1. I seem to have a natural aptitude for data entry and they don't (I have done 'temp' jobs doing data entry through agencies before, although my current role doesn't have anything to do with data entry) and 2. I noticed that they were chatting, bantering and generally taking their time over this task.
So after completing my batch of 20 things I packed up my stuff and left. (There wasn't any "coordination" work that needed to be done after -- it was literally enter these things and then it's done).
The others were there for about an hour longer as I understand it.
Next day the supervisor had a word with me - he was "disappointed" and "dismayed" that I had just packed up my stuff and left, leaving the others to it. In his view I should have hung around and picked up some of their "still not done" items. (Remember we were each allocated the same number of items, of equal difficulty, but the others were just slower than I was).
My question is whether I was in the wrong, should I have hung around and taken some of the rest of the workload from the others so that we could all leave earlier? Was this a professional thing to do or were there other, better alternatives?
In some sense it's a fairly petty question since we are talking about a max of a couple of hours extra time (if in the extreme case the others refused to do anything and I had had to do all of it), but I feel it's the principle that's at stake. An equal amount of work (that wasn't even ours to complete!) being given to each person, I happened to complete it earlier so I didn't see any obligation to help out the others.