Yup, but if the speedypiss user is on a VIP pass they can sit there repeatedly, though admittedly they would come back into the station on the other platform, courtesy of Mr Mobius, and the gap between trains can often be the best part of ten minutes if the staff are taking their time, even if all four trains are in use, because of the crap KumbaK station system.
The busier the day, the more likely the train will be half full of queue jumper punters as it gets to the airgates, the trick is to not go for the front or back seats on busy days, as the seats are likely to be taken before the train gets into the station