DRUK "Really?"
I can't tell from your post 2 whether you think that the figure of seven minutes is an over- or an underestimate. The article linked to states that there are (presumably "were" since the article is dated 6th January 2013) 1068 flights a week. Hopefully, this is 2136 "operations" per week.
One week is 7 days/week X 24 hours/day X 60 minutes/hour or 10,080 minutes. So, 10,080 minutes/2136 operations gives approximately 4.72 minutes per operation.
This is quite a bit less than the calculation quoted although within the same order of magnitude. I suspect that the author has regurgitated an impressive-sounding calculation that has been doing the rounds since the time when there were far fewer A380s flying. Journalism eh?
However, as a critique of the arithmetic, you are quite correct.
SFS