I read this so much, but the reality is anyone who is used to travelling in US, need only arrive at the gate at the same time (or even later) than they would in the US. Gates close strictly 10 mins before departure for SQ at SIN, But never seen one close much more than this unless all pax have boarded, and for example I would reach gate in the US no later than 30 mins before, and at SIN that's not a problem.