For that reason the Nexus/Canpass is really wonderful. Just got back on a flight from SIN on SQ, as usual and as described the hall was filled with hundreds of people arriving from Asia. No-one at the Canpass machines. Took 1 minute to get through, with no luggage time from leaving the airplane to leaving the airport is about 10 - 15 minutes.
The $ 50.00 fee a year is well worth it. And of course the NEXUS pass works at the US pre clearance facility as well.