crowd start on 11AM >

So sorry for the too late answer. Hope it was not too crowded for you.

Normally I always avoid the weekend and public holiday.

I went on a Tuesday at 10:30am after the initial wave of people who go as it opens. Waited 5 min in queue and was the only one up on the roof gallery. Perfect!

The set up of the ticket counters would make for a Long wait at peak times!

Hello there! There's always a long queue at the National Gallery of Singapore any time of the day, especially on week-ends. The best thing to do is to visit the place on week days and to buy your ticket on-line. Enjoy!