When I was down there not long ago, the swipe system only allowed one swipe per minute. Perhaps the even figure of 1200 is the diagnostic allowance of credits permitted per day?

I was there less then 3 weeks ago and spent two full (peak hour) sesssions there. I would like to point out:=

1: As per above - per card - you cannot add more credits.  There is a minute delay with the card.  You swipe - you then cannot swipe for another minute.  You can't just keep adding credits and keep swiping (albeit waiting a minute into your game then swiping - however I saw no one doing this).
2: I never saw anyone playing doubles or triples on the pinball machines. 
3: What hasn't been discussed yet is that 95% of the people that go there get the package deals - esp in the school holidays.  http://www.timezonegoldcoast.com.au/packages.  I normally get the $25 combo and spend 2 hours smashing the games with the kids before we move off onto the dodgems and laser skirmish.  I will have at least 10+ games on the pinball machines that are there - plus the other arcade machines.  The machines that I play on HAVEN"T brought in $1:50 per swipe (from me anyway).  It is far less - considering the package deal and all the other machines and games that I also used my card on. 
4: While I was on them - I found casual traffic flow - but they weren't packed.

Same as 4_amusement_only - I was more then happy to give them my business just to be able to play some of the latest release pins - for a very economical price.