The Immigration and Checkpoints Authority has warned people to expect heavy traffic flow at both Woodlands and Tuas land checkpoints over the Labour Day long weekend. It's advisable that you do whatever you can to avoid leaving Singapore on Apr 29 and entering on May 2. (If you didn't already know that, welcome to Singapore. You must be new.)
Traffic build-up is inevitable with the hordes of people who usually descend upon the checkpoints over long weekends, so adjust your plans or you'll have to endure hours of waiting. Plus, with the implementation of the BioScreen system to capture thumbprints of arriving and departing visitors, things might take a little longer.
Out of all the tips from the ICA, which include maintaining lane discipline, this one's probably the most useful: car-pool. And, of course, don't forget your passport.